chore(docs): extend docs on golang inputs

This documents all of the inputs that can be passed to the
`golangci_lint.yml` CI- template.

golangci-lint.md

@@ -18,3 +18,15 @@ include:
     inputs:
       golangci_lint_timeout: 5m # optionally specify a separate timeout
 ```
+
+## Configuration
+
+This template receives the following input variables:
+
+- `stage`: The stage in which the `golangci_lint` job runs
+  Default: `validate`
+- `docker_hub_host`: The docker hub host from which to pull the
+  `golangci-lint` image.
+  Default: `docker.io`
+- `golangci_lint_timeout`: The timeout used for `golangci-lint`
+  Default: `5m`

templates/golang.md

@@ -48,3 +48,10 @@ include:
       validate_stage: test  # stage that validation jobs should run in
       release_stage: deploy  # stage that release jobs should run in
 ```
+
+## Other configuration
+
+The following values can also be configured and are passed to the
+relevant tasks:
+
+- `golangci_lint_timeout`: [`golangci-lint.yml`](../golangci-lint.md)