Adding in configuration page for administration guide.

docs/administration-guide/gaffer-config/config.md

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+## How to configure a Gaffer instance
+
+First you must set up the files and directories you will need for the instance. As it stands there
+are a couple of different ways to run a Gaffer project this example will use a logical structure
+that suites a stand alone deployment consisting of the following file structure:
+
+!!! example "Example Gaffer project structure"
+
+    !!! tip ""
+        Click the plus symbols for a brief description of each file
+
+    ```yaml
+    ├── config
+    │   ├── gaffer
+    │       ├── application.properties #(1)!
+    │       ├── data                   #(2)!
+    │       │   ├── neo4jExport.csv
+    │       ├── graph
+    │       │   └── graphConfig.json #(3)!
+    │       ├── schema
+    │       │   ├── elements.json #(4)!
+    │       │   └── types.json    #(5)!
+    │       └── store
+    │           ├── operationsDeclarations.json #(6)!
+    │           └── store.properties            #(7)!
+    │   
+    └── docker-compose.yaml #(8)!
+    ```
+
+    1. Properties file that generally sets the file locations of other Gaffer
+        configs e.g. schemas (note these are the absolute paths inside the
+        container).
+    2. Any data files, e.g. CSV, to be made available to the Gaffer container.
+    3. The main graph config file to set various properties of the overall graph.
+    4. This file holds the schema outlining the elements in the graph, e.g. the
+    nodes (aka entities) and edges.
+    5. This file defines the different data types in the graph and how they are
+    serialised to Java classes.
+    6. Config file for additional Gaffer operations and set the class to handle
+    them on the store.
+    7. The General store properties, sets up what store to use and any additional
+    configuration.
+    8. This file controls which containers will be started up and the configuration
+    of them to ensure correct ports and files are available.
+
+All the files in the `config/accumulo/` and `config/hdfs/` directories will be copied directly from
+the two locations in the Gaffer docker repo,
+[here](https://github.com/gchq/gaffer-docker/tree/develop/docker/accumulo/conf-2.0.1) and
+[here](https://github.com/gchq/gaffer-docker/tree/develop/docker/hdfs/conf). The configuration of
+these are out of scope of this example but are covered in other sections of the documentation. The
+main focus of this guide will be on the configuration files under the `config/gaffer/` directory.
+
+## Configuration Files
+
+### Application Properties
+
+This is probably the simplest configuration file in the Gaffer deployment. In general it borrows a
+concept from [Spring Boot](https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html)
+to allow changing the context root and any properties related to Gaffer. In the example that follows
+we use it to set the file location properties of where the other config files are (inside the
+container).
+
+```properties title="application.properties"
+gaffer.schemas=/gaffer/schema
+gaffer.storeProperties=/gaffer/store/store.properties
+gaffer.graph.config=/gaffer/graph/graphConfig.json
+```
+
+### Graph Configuration
+
+The graph configuration file is a JSON file that configures few bits of the Gaffer graph. Primarily
+it is used to set the name and description along with any additional hooks to run before an operation
+chain e.g. to impose limits on max results etc. For the example as, it is a very basic graph we just
+set the name and short description.
+
+```json title="graphConfig.json"
+{
+    "graphId": "ExampleGraph",
+    "description": "An example graph"
+}
+```
+
+### Store Properties
+
+The store properties file is used to configure how Gaffer will store its data. There are a few
+different stores available for Gaffer, these are explained in more detail in the [reference
+documentation](../../administration-guide/gaffer-stores/store-guide.md), but by default you must provide a store
+class and a store properties class. For this example we are using an Accumulo store as it is
+recommended for efficient storage and retrieval of large data volumes. It's set up requires a few
+custom properties which are outlined in the following file.
+
+```properties title="store.properties"
+gaffer.store.class=uk.gov.gchq.gaffer.accumulostore.AccumuloStore
+gaffer.store.properties.class=uk.gov.gchq.gaffer.accumulostore.AccumuloProperties
+
+# Accumulo specific config
+accumulo.instance=accumulo
+accumulo.zookeepers=zookeeper
+accumulo.user=root
+accumulo.password=secret
+
+# General store config
+gaffer.cache.service.class=uk.gov.gchq.gaffer.cache.impl.HashMapCacheService
+gaffer.store.job.tracker.enabled=true
+gaffer.store.operation.declarations=/gaffer/store/operationsDeclarations.json
+```
+
+### Operations Declarations
+
+The operation declarations file is a way of enabling additional operations in Gaffer. By default
+there are some built in operations already available (the rest API has a get all operations request
+to see a list), but its likely you might want to enable others or add your own custom ones. As the
+example will load its data from a local CSV file we can activate a couple of additional operations
+using the following file.
+
+```json title="operationsDeclarations.json"
+{
+    "operations": [
+        {
+            "operation": "uk.gov.gchq.gaffer.operation.impl.export.localfile.ImportFromLocalFile",
+            "handler": {
+                "class": "uk.gov.gchq.gaffer.store.operation.handler.export.localfile.ImportFromLocalFileHandler"
+            }
+        },
+        {
+            "operation": "uk.gov.gchq.gaffer.operation.impl.export.localfile.ExportToLocalFile",
+            "handler": {
+                "class": "uk.gov.gchq.gaffer.store.operation.handler.export.localfile.ExportToLocalFileHandler"
+            }
+        }
+    ]
+}
+```
+
+The two additional operations already exist in Gaffer (in the code base:
+[ImportFromLocalFile](https://github.com/gchq/Gaffer/blob/develop/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/export/localfile/ImportFromLocalFile.java)
+and
+[ExportToLocalFile](https://github.com/gchq/Gaffer/blob/develop/core/operation/src/main/java/uk/gov/gchq/gaffer/operation/impl/export/localfile/ExportToLocalFile.java)),
+what this file is doing is essentially activating them and setting the handler class for them. The
+`ImportFromLocalFile` usage is demonstrated in the [using the API](./using-the-api.md) section to
+load some data.
+
+This operation allows us to pass a local CSV file (in the container) which will be read line by line
+and get a stream of the line strings. This is very useful when we start using Operation Chains as
+we can pass this stream of data as the input to the next operation in the chain similar to shell
+pipes.
+
+!!! note
+    The location of the file needs to be set via the store properties file using the
+    `gaffer.store.operation.declarations` property (see [previous section](#store-properties)).