documentation: Mention which external toolchains we tested

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

docs/buildroot.html

@@ -748,11 +748,12 @@ endif
       correspond to your cross-compiling tools</li>
     </ul>
 
-    <p>To generate external toolchains, we recommend using
-    <a href="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool">Crosstool-NG</a>.
-    It allows generating toolchains based on <i>uClibc</i>, <i>glibc</i>
-    and <i>eglibc</i> for a wide range of architectures and has good
-    community support.</p>
+    <p>Our external toolchain support has been tested with toolchains
+    from CodeSourcery, toolchains generated
+    by <a href="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool">Crosstool-NG</a>,
+    and toolchains generated by Buildroot itself. In general, all
+    toolchains that support the <i>sysroot</i> feature should
+    work. If not, do not hesitate to contact the developers.</p>
 
     <h2 id="add_packages">Adding new packages to Buildroot</h2>