UI: Inform user what meaning hourglass on reviews has (#12713)

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

options/locale/locale_en-US.ini

@@ -1027,6 +1027,7 @@ issues.poster = Poster
 issues.collaborator = Collaborator
 issues.owner = Owner
 issues.re_request_review=Re-request review
+issues.is_stale = There have been changes to this PR since this review
 issues.remove_request_review=Remove review request
 issues.remove_request_review_block=Can't remove review request
 issues.sign_in_require_desc = <a href="%s">Sign in</a> to join this conversation.

templates/repo/issue/view_content/pull.tmpl

@@ -27,7 +27,7 @@
 						</div>
 						<div class="review-item-right">
 							{{if .Stale}}
-							<span class="type-icon text grey">
+							<span class="ui poping up type-icon text grey" data-content="{{$.i18n.Tr "repo.issues.is_stale"}}">
 								<i class="octicon icon fa-hourglass-end"></i>
 							</span>
 							{{end}}