Fix markup content overflow (go-gitea#34072)

Fix go-gitea#34069: use `overflow-wrap: anywhere` to correctly wrap overflowed
content.

(cherry picked from commit 0fd5392)

Author: kerwin612

web_src/css/markup/content.css

@@ -2,7 +2,7 @@
   overflow: hidden;
   font-size: 16px;
   line-height: 1.5 !important;
-  word-wrap: break-word;
+  overflow-wrap: anywhere;
 }
 
 .markup > *:first-child {