Navigation tree doesn't render due to \n in output

Due to a construct like:
```
---
Example:
  - -w '%{response_code}\n' $URL
---

# Section

Section

## Sub Section
subsection
```

where the GitHub construct with the `---` is always interpreted as a header.
By removing the the `\n` from the navtree JavaScript output the problem is solved.

Author: albert-github

src/ftvhelp.cpp

@@ -556,6 +556,7 @@ static void generateJSLink(TextStream &t,const FTVNodePtr &n)
 {
   bool nameAsHtml = !n->nameAsHtml.isEmpty();
   QCString link = nameAsHtml ? convertToJSString(n->nameAsHtml,true) : convertToJSString(n->name);
+  link = substitute(link,"\n","");
   if (n->file.isEmpty()) // no link
   {
     t << "\"" << link << "\", null, ";