docs/dispatch: Fix nonexistent paths
What does this MR do and why?
docs/dispatch: Fix nonexistent paths
Since 296adbd545b8 ("glapi: Move to src/mapi/.") `src/mesa/glapi`
has been refactored to `src/mapi/glapi`, so should update these path
references accordingly.
Signed-off-by: Luc Ma <luc@sietium.com>