docs: update sourcetree following omx rename

Fixes: 6a8aa11c207b99920b93 "st/omx_bellagio: Rename state tracker and option"
Cc: Gurkirpal Singh <gurkirpal204@gmail.com>
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Andres Gomez <agomez@igalia.com>
diff --git a/docs/sourcetree.html b/docs/sourcetree.html
index 9448df5..07c8ece 100644
--- a/docs/sourcetree.html
+++ b/docs/sourcetree.html
@@ -145,7 +145,7 @@
        <li><b>xvmc</b> - XvMC state tracker
        <li><b>vdpau</b> - VDPAU state tracker
        <li><b>va</b> - VA-API state tracker
-       <li><b>omx</b> - OpenMAX state tracker
+       <li><b>omx_bellagio</b> - OpenMAX Bellagio state tracker
        </ul>
     <li><b>winsys</b> -
        <ul>