gallium/docs: Add Galahad
diff --git a/src/gallium/docs/source/debugging.rst b/src/gallium/docs/source/debugging.rst
index 42bda5a..e081cbf 100644
--- a/src/gallium/docs/source/debugging.rst
+++ b/src/gallium/docs/source/debugging.rst
@@ -21,6 +21,10 @@
is probably the most useful variable, since it allows you to find which
variables a driver uses.
+.. envvar:: GALLIUM_GALAHAD <bool> (false)
+
+Controls if the :ref:`galahad` sanity checker module should be used.
+
.. envvar:: GALLIUM_RBUG <bool> (false)
Controls if the :ref:`rbug` should be used.