docs/docs.html: Point users to html asciidoc documentation

Rather than the outdated buildroot.html. The asciidoc documentation is
still not autogenerated from git, instead a static snapshot is made per
release (like we did for /downloads/buildroot.html).

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/docs.html

@@ -2,15 +2,10 @@
 
 <h3>Documentation</h3>
 
-<p>Our document "Buildroot usage and documentation" is where you want
-to start reading if you wish to understand how Buildroot work, or wish
-to change/extend/fix things. If you find any errors (factual,
-grammatical, whatever) please report them. Choose between:</p>
-
-<ul>
-  <li><a href="/downloads/buildroot.html">Latest stable release</a></li>
-  <li><a href="buildroot.html">GIT head revision</a></li>
-</ul>
+<p>The <a href="/downloads/manual/manual.html">Buildroot user manual</a>
+is where you want to start reading if you wish to understand how
+Buildroot works, or wish to change/extend/fix things. If you find any
+errors (factual, grammatical, whatever) please report them to us.</p>
 
 <p>If you find that you need help with Buildroot, you can ask for
 help:</p>