doc: pytest: Document the test_bind test

Add this test to the documentation. None of the functions had comments,
so attempt to explain what each does.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/develop/pytest/index.rst b/doc/develop/pytest/index.rst
index 3265eb9..cd6eb5f 100644
--- a/doc/develop/pytest/index.rst
+++ b/doc/develop/pytest/index.rst
@@ -18,6 +18,7 @@
    :maxdepth: 1
 
    test_000_version
+   test_bind
    test_bootstage
    test_efi_loader
    test_net