Merge branch '229553-feature-flag-block' into 'master'

Add feature flag block for schema based validation

See merge request gitlab-org/gitlab!38137

doc/user/project/web_ide/index.md

@@ -31,8 +31,6 @@ file path fragments to start seeing results.
 
 ## Syntax highlighting
 
-> Support for `.gitlab-ci.yml` validation [introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/218472) in GitLab 13.2.
-
 As expected from an IDE, syntax highlighting for many languages within
 the Web IDE will make your direct editing even easier.
 
@@ -44,14 +42,6 @@ The Web IDE currently provides:
 - IntelliSense and validation support (displaying errors and warnings, providing
   smart completions, formatting, and outlining) for some languages. For example:
   TypeScript, JavaScript, CSS, LESS, SCSS, JSON, and HTML.
-- Validation support for certain JSON and YAML files using schemas based on the
-  [JSON Schema Store](https://www.schemastore.org/json/). This feature
-  is only supported for the `.gitlab-ci.yml` file.
-
-  NOTE: **Note:**
-  Validation support based on schemas is hidden behind
-  the feature flag `:schema_linting` on self-managed installations. To enable the
-  feature, you can [turn on the feature flag in Rails console](../../../administration/feature_flags.md#how-to-enable-and-disable-features-behind-flags).
 
 Because the Web IDE is based on the [Monaco Editor](https://microsoft.github.io/monaco-editor/),
 you can find a more complete list of supported languages in the
@@ -63,6 +53,37 @@ If you are missing Syntax Highlighting support for any language, we prepared a s
 NOTE: **Note:**
 Single file editing is based on the [Ace Editor](https://ace.c9.io).
 
+### Schema based validation
+
+> - Support for `.gitlab-ci.yml` validation [introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/218472) in GitLab 13.2.
+> - It was deployed behind a feature flag, disabled by default.
+> - It's enabled on GitLab.com.
+> - It cannot be enabled or disabled per-project.
+> - For GitLab self-managed instances, GitLab administrators can opt to [enable it](#enable-or-disable-schema-based-validation-core-only).
+
+The Web IDE provides validation support for certain JSON and YAML files using schemas
+based on the [JSON Schema Store](https://www.schemastore.org/json/). This feature is
+only supported for the `.gitlab-ci.yml` file.
+
+#### Enable or disable Schema based validation **(CORE ONLY)**
+
+Schema based validation is under development and not ready for production use. It is
+deployed behind a feature flag that is **disabled by default** for self-managed instances,
+[GitLab administrators with access to the GitLab Rails console](../../../administration/feature_flags.md)
+can enable it for your instance.
+
+To enable it:
+
+```ruby
+Feature.enable(:schema_linting)
+```
+
+To disable it:
+
+```ruby
+Feature.disable(:schema_linting)
+```
+
 ### Themes
 
 > - [Introduced](https://gitlab.com/groups/gitlab-org/-/epics/2389) in GitLab in 13.0.