Add missing flags for the astro check command

src/content/docs/en/reference/cli-reference.mdx

@@ -226,6 +226,36 @@ Use these flags to customize the behavior of the command.
 
 The command will watch for any changes in your project, and will report any errors.
 
+#### `--root <path-to-dir>`
+
+Specify a different root directory to check. Uses the current working directory by default.
+
+#### `--tsconfig <path-to-file>`
+
+Specify a `tsconfig.json` or `jsconfig.json` file to use manually. If not provided, Astro will attempt to find a config, or infer the project's config automatically.
+
+#### `--minimumFailingSeverity <error|warning|hint>`
+
+Default: `error`
+
+Minimum severity needed to exit with an error code.
+
+For example, chooisng `warning` will cause the command to exit with an error if any warnings are detected.
+
+#### `--minimumSeverity <error|warning|hint>`
+
+Default: `hint`
+
+Minimum severity to output.
+
+For example, choosing `warning` will show errors and warnings, but not hints.
+
+#### `--preserveWatchOutput`
+
+Default: `false`
+
+If set to false, the output will not be cleared between checks when in watch mode.
+
 <ReadMore>Read more about [type checking in Astro](/en/guides/typescript/#type-checking).</ReadMore>
 
 ## `astro sync`