docs/devinfo: Update bullet in stale extension guide

Signed-off-by: Nanley Chery <nanley.g.chery@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
diff --git a/docs/devinfo.html b/docs/devinfo.html
index 70141ae..f5d23ab 100644
--- a/docs/devinfo.html
+++ b/docs/devinfo.html
@@ -686,7 +686,7 @@
    Add a new entry to the <code>gl_extensions</code> struct in mtypes.h
 </li>
 <li>
-   Update the <code>extensions.c</code> file.
+   Add a new entry to the src/mesa/main/extensions_table.h file.
 </li>
 <li>
    From this point, the best way to proceed is to find another extension,