Waring with ingroup command at end of alias

When having the simple problem:
```

/** @defgroup dm dep mac */

/** @old{ONIGENC_MBCLEN_CHARFOUND_P} */
int fnmatch_helper()
{
}
```
with
```
QUIET = YES
ALIASES                = "old{1}=@InGroup dm"
INPUT = pp.c

```
we get the warning like:
```
pp.c:6: warning: Found non-existing group 'br' for the command '@InGroup', ignoring command
```

By first ending the command before adding the `<br>`

Author: albert-github

src/markdown.cpp

@@ -2687,7 +2687,7 @@ void Markdown::Private::writeOneLineHeaderOrRuler(std::string_view data)
 
     if (hasLineBreak(data))
     {
-      out+="<br>";
+      out+="\\ilinebr<br>";
     }
     if (tmpSize != data.size()) out+='\n';
   }