docs: Add heading to justification explanation

Places the documentation related to justifications (on comment directives) in its own section so it may be more easily found from the table of contents.

Fixes #16426

docs/src/user-guide/configuring/rules.md

@@ -232,6 +232,10 @@ foo(); // eslint-disable-line example/rule-name
 foo(); /* eslint-disable-line example/rule-name */
 ```
 
+**Note:** Comments that disable warnings for a portion of a file tell ESLint not to report rule violations for the disabled code. ESLint still parses the entire file, however, so disabled code still needs to be syntactically valid JavaScript.
+
+#### Documenting justification
+
 Configuration comments can include descriptions to explain why the comment is necessary. The description must come after the configuration and needs to be separated from the configuration by two or more consecutive `-` characters. For example:
 
 ```js
@@ -245,8 +249,6 @@ console.log('hello');
 console.log('hello');
 ```
 
-**Note:** Comments that disable warnings for a portion of a file tell ESLint not to report rule violations for the disabled code. ESLint still parses the entire file, however, so disabled code still needs to be syntactically valid JavaScript.
-
 ### Using configuration files
 
 To disable rules inside of a configuration file for a group of files, use the `overrides` key along with a `files` key. For example: