Satisfy theme check

WaffleLapkin · WaffleLapkin · commit 7f1af4219082 · 2022-07-24T16:48:35.000+04:00
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
@@ -205,6 +205,7 @@ details.rustdoc-toggle > summary::before {
 
 /* Created this empty rule to satisfy the theme checks. */
 .stab.empty-impl {}
+.stab.must_implement {}
 
 .stab.unstable,
 .stab.deprecated,
