Describe building contract and query creation

Author: jawoznia

docs-test-gen/templates/empty.tpl

@@ -1,6 +1,7 @@
 #![allow(unexpected_cfgs, dead_code, unused_variables)]
 
+{{code}}
+
 #[test]
 fn doctest() {
-  {{code}}
 }

src/pages/tutorial/cw-contract/_meta.json

@@ -1,4 +1,6 @@
 {
   "contract-creation": "Contract creation",
-  "entry-points": "Entry points"
+  "entry-points": "Entry points",
+  "building-contract": "Building contract",
+  "query": "Creating a query"
 }

src/pages/tutorial/cw-contract/building-contract.mdx

@@ -0,0 +1,59 @@
+# Building the contract
+
+Now it is time to build our contract. We can use a traditional cargo build pipeline for local
+testing purposes: `cargo build` for compiling it and `cargo test` for running all tests (which we
+don't have yet, but we will work on that soon).
+
+However, we need to create a wasm binary to upload the contract to blockchain. We can do it by
+passing an additional argument to the build command:
+
+```shell copy filename="TERMINAL"
+cargo build --target wasm32-unknown-unknown --release
+```
+
+The `--target` argument tells cargo to perform cross-compilation for a given target instead of
+building a native binary for an OS it is running on - in this case, `wasm32-unknown-unknown`, which
+is a fancy name for Wasm target.
+
+Additionally, I passed the `--release` argument to the command - it is not required, but in most
+cases, debug information is not very useful while running on-chain. It is crucial to reduce the
+uploaded binary size for gas cost minimization. It is worth knowing that there is a
+[CosmWasm Rust Optimizer](https://github.com/CosmWasm/rust-optimizer) tool that takes care of
+building even smaller binaries. For production, all the contracts should be compiled using this
+tool, but for learning purposes, it is not an essential thing to do.
+
+## Aliasing build command
+
+Now I can see you are disappointed in building your contracts with some overcomplicated command
+instead of simple `cargo build`. Fortunately, it is not the case. The common practice is to alias
+the building command to make it as simple as building a native app.
+
+Let's create the `.cargo/config.toml` file in your contract project directory with the following
+content:
+
+```toml copy filename=".cargo/config.toml"
+[alias]
+wasm = "build --target wasm32-unknown-unknown --release"
+wasm-debug = "build --target wasm32-unknown-unknown"
+```
+
+Now, building your Wasm binary is as easy as executing `cargo wasm`. We also added the additional
+`wasm-debug` command for rare cases when we want to build the wasm binary, including debug
+information.
+
+## Checking contract validity
+
+When the contract is built, the last step is to ensure it is a valid CosmWasm contract is to call
+`cosmwasm-check` on it:
+
+```shell copy filename="TERMINAL"
+cargo wasm && cosmwasm-check ./target/wasm32-unknown-unknown/release/contract.wasm
+```
+
+```shell filename="TERMINAL"
+Available capabilities: {"cosmwasm_1_2", "cosmwasm_1_4", "stargate", "cosmwasm_1_1", "cosmwasm_2_1", "cosmwasm_1_3", "cosmwasm_2_0", "staking", "iterator"}
+
+./target/wasm32-unknown-unknown/release/contract.wasm: pass
+
+All contracts (1) passed checks!
+```