doc: remove problematic auto-linking of curl man pages
The only instance of curl man page linking is in repl.md and it is explicit. The magic autolinking in html.js creates a superfluous empty link. Remove it.
Before, two adjacent links generated, with the first one having no text:
<a href="https://curl.haxx.se/docs/manpage.html"></a>
<a href="https://curl.haxx.se/docs/manpage.html"><code>curl(1)</code></a>
After, just one link:
<a href="https://curl.haxx.se/docs/manpage.html"><code>curl(1)</code></a>
Checklist
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documentation is changed or added -
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