improve explore relevancy note (#22421)

makes the explore relevancy note much prettier on most themes

templates/explore/repo_search.tmpl

@@ -30,7 +30,7 @@
 	</div>
 </form>
 {{if .OnlyShowRelevant}}
-	<div class="ui blue attached message explore-relevancy-note">
+	<div class="ui message explore-relevancy-note">
 		<span class="ui tooltip" data-content="{{.locale.Tr "explore.relevant_repositories_tooltip"}}">{{.locale.Tr "explore.relevant_repositories" ((printf "%s%s" $.Link "?no_filter=1")|Escape) | Safe}}</span>
 	</div>
 {{end}}