Improve docker image README (#8212)

* Improve docker image README

- Fix unnecessary/missing newline escapes
- Remove double whitespace between parameters
- 2-space indent for extra lines in image build commands

* Add changelog entry for #8212

.changes/unreleased/Docs-20230728-193438.yaml

@@ -0,0 +1,6 @@
+kind: Docs
+body: Fix newline escapes and improve formatting in docker README
+time: 2023-07-28T19:34:38.351042747+02:00
+custom:
+  Author: jamezrin
+  Issue: "8211"

docker/README.md

@@ -15,7 +15,7 @@ This Dockerfile can create images for the following targets, each named after th
 
 In order to build a new image, run the following docker command.
 ```
-docker build --tag <your_image_name>  --target <target_name> <path/to/dockerfile>
+docker build --tag <your_image_name> --target <target_name> <path/to/dockerfile>
 ```
 ---
 > **Note:**  Docker must be configured to use [BuildKit](https://docs.docker.com/develop/develop-images/build_enhancements/) in order for images to build properly!
@@ -54,17 +54,17 @@ docker build --tag <your_image_name> \
 To build an image named "my-dbt" that supports redshift using the latest releases:
 ```
 cd dbt-core/docker
-docker build --tag my-dbt  --target dbt-redshift .
+docker build --tag my-dbt --target dbt-redshift .
 ```
 
 To build an image named "my-other-dbt" that supports bigquery using `dbt-core` version 0.21.latest and the bigquery adapter version 1.0.0b1:
 ```
 cd dbt-core/docker
 docker build \
-  --tag my-other-dbt  \
+  --tag my-other-dbt \
   --target dbt-bigquery \
   --build-arg [email protected] \
-  --build-arg [email protected]  \
+  --build-arg [email protected] \
  .
 ```
 
@@ -87,27 +87,28 @@ There are a few special cases worth noting:
 docker build --tag my_dbt \
   --target dbt-postgres \
   --build-arg [email protected] \
-  <path/to/dockerfile> \
-  ```
+  <path/to/dockerfile>
+```
 
 * If you need to build against another architecture (linux/arm64 in this example) you can overide the `build_for` build arg:
 ```
 docker build --tag my_dbt \
   --target dbt-postgres \
   --build-arg build_for=linux/arm64 \
-  <path/to/dockerfile> \
-  ```
+  <path/to/dockerfile>
+```
+
 Supported architectures can be found in the python docker [dockerhub page](https://hub.docker.com/_/python).
 
 ## Running an image in a container:
 The `ENTRYPOINT` for this Dockerfile is the command `dbt` so you can bind-mount your project to `/usr/app` and use dbt as normal:
 ```
 docker run \
---network=host
---mount type=bind,source=path/to/project,target=/usr/app \
---mount type=bind,source=path/to/profiles.yml,target=/root/.dbt/profiles.yml \
-my-dbt \
-ls
+  --network=host \
+  --mount type=bind,source=path/to/project,target=/usr/app \
+  --mount type=bind,source=path/to/profiles.yml,target=/root/.dbt/profiles.yml \
+  my-dbt \
+  ls
 ```
 ---
 **Notes:**