Mention test-config phase in config docs
I had to dig into the stack.sh code to figure out why
my tempest.conf post-config wasn't work, and it's because
post-config isn't the thing to use to configure tempest,
test-config is.
Change-Id: Ic5bbe36b5d44880d0a3a602f653b4f61fd89e9c8
Related-Bug: #1755947
diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 1d02395..fc0a620 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -41,6 +41,7 @@
- **extra** - runs after services are started and before any files in
``extra.d`` are executed
- **post-extra** - runs after files in ``extra.d`` are executed
+- **test-config** - runs after tempest (and plugins) are configured
The file is processed strictly in sequence; meta-sections may be
specified more than once but if any settings are duplicated the last to