Add missing flags for the astro check command (withastro#8237)

Co-authored-by: Atharva <atharvapise19@gmail.com>
Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

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

@@ -226,6 +226,30 @@ 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>`
+
+Specifies a different root directory to check. Uses the current working directory by default.
+
+#### `--tsconfig <path-to-file>`
+
+Specifies 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>`
+
+Specifies the minimum severity needed to exit with an error code. Defaults to `error`.
+
+For example, running `astro check --minimumFailingSeverity warning` will cause the command to exit with an error if any warnings are detected.
+
+#### `--minimumSeverity <error|warning|hint>`
+
+Specifies the minimum severity to output. Defaults to `hint`.
+
+For example, running `astro check --minimumSeverity warning` will show errors and warning, but not hints.
+
+#### `--preserveWatchOutput`
+
+Specifies not to clear the ouput between checks when in watch mode.
+
 <ReadMore>Read more about [type checking in Astro](/en/guides/typescript/#type-checking).</ReadMore>
 
 ## `astro sync`