added ignore command in the doc (#131)

Author: dikshant-coderabbit

docs/guides/commands.md

@@ -11,6 +11,7 @@ The following commands are available (invoked as PR comments):
 
 -`@coderabbitai pause` to pause the reviews on a PR.
 -`@coderabbitai resume` to resume the paused reviews.
+-`@coderabbitai ignore` to ignore the reviews on a PR.
 -`@coderabbitai review` to trigger an incremental review. This is useful when
  automatic reviews are disabled for the repository.
 -`@coderabbitai full review` to do a full review from scratch and review all