Document, add to changelog the data migrations and rename to 'warnings-as-errors' (plural)

docs/incompatibilities.md

@@ -12,3 +12,10 @@ The linter analyses your migrations and checks the SQL for:
 
 Those are the most important and frequent backward incompatible migrations.
 We are happy to add more if you can specify them to us.
+
+
+## Warnings
+
+On data migrations, the linter will show a warning when:
+* you are missing a reverse migration
+* the RunPython arguments do not respect the naming convention `apps, schema_editor`

docs/usage.md

@@ -25,6 +25,7 @@ Detailed command line options:
 |`--project-root-path DJANGO_PROJECT_FOLDER`                   | An absolute or relative path to the django project.                                                                         |
 |`--include-migrations-from FILE_PATH`                         | If specified, only migrations listed in the given file will be considered.                                                  |
 |`--quiet or -q {ok,ignore,warning,error}`                     | Suppress certain output messages, instead of writing them to stdout.                                                        |
+|`--warnings-as-errors`                                        | Handle warnings as errors and therefore return an error status code if we should.                                           |
 
 ## Ignoring migration tests