docs(ignition): add environment variable reference

Added docs for:

* `HARDHAT_IGNITION_CONFIRM_DEPLOYMENT`
* `HARDHAT_IGNITION_CONFIRM_RESET`

Author: kanej

docs/src/content/ignition/docs/reference/_dirinfo.yaml

@@ -0,0 +1,4 @@
+section-type: group
+section-title: Reference
+order:
+  - /environment-variables

docs/src/content/ignition/docs/reference/environment-variables.md

@@ -0,0 +1,6 @@
+# Environment variables
+
+Hardhat Ignition supports special environment variables that affects how deployment works:
+
+- `HARDHAT_IGNITION_CONFIRM_DEPLOYMENT`: if set to `false`, Hardhat Ignition won't prompt the user asking for confirmation when deploying to a live network. This prompt is already not shown when running against the local Hardhat network (chainId: 31337), but you might want to set this variable if writing fully automated scripts that leverage Hardhat Ignition.
+- `HARDHAT_IGNITION_CONFIRM_RESET`: if set to `false`, Hardhat Ignition won't prompt the user asking for confirmation when overwritting the previous deployment via the `--reset` flag on Hardhat Ignition's `deploy` task.

docs/src/content/layouts.yaml

@@ -55,6 +55,7 @@ ignition:
     - ignition/docs/config
     - ignition/docs/guides
     - ignition/docs/advanced
+    - ignition/docs/reference
     - ignition/docs/other-components
 
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