[DOCS] Clarify when `index` parameter is required for Watcher index action (#81566) (#81608)
[DOCS] Clarify when `index` parameter is required for Watcher index action (#81566) (#81608)

If you dynamically add an `_index` value, the `index` parameter is not required for the Watcher index action.

Co-authored-by: James Rodewig <40268737+jrodewig@users.noreply.github.com>
# Conflicts:
#	x-pack/docs/en/watcher/actions/index.asciidoc

Co-authored-by: Daisuke Harada <b1fd0f87a909378b990d1acdb0cadfdd42e22f5e@users.noreply.github.com>
GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch