add link to gallium docs.. not freedreno specific but useful link to have handy when hacking on the mesa parts

Home.md

@@ -11,6 +11,7 @@
   * [[Adreno Tiling|Adreno-Tiling]] - how tiling works on adreno (a2xx and a3xx)
   * [[A2xx Shader Instruction Set Architecture|A2XX-Shader-Instruction-Set-Architecture]]
   * [[A3xx Shader Instruction Set Architecture|A3XX-Shader-Instruction-Set-Architecture]]
+  * [Gallium Docs](http://gallium.readthedocs.org/en/latest/)
 * [[Setting up fedora filesystem|Fedora]]
 * [[Frequently Asked Questions|FAQ]]
 * [[TODO|TODO]]