Unselect RBAC goal to rework the implementation

As discussed in Yoga PTG, we need to rework the implementation
for the new secure RBAC.
- https://etherpad.opendev.org/p/tc-yoga-ptg

We will continue to rework the implementation in
goals/proposed folder and once it is ready then we will select this
as goal.

Change-Id: I1ce58b1c42ce1e24116a54b6fc136bf6bbcdc818

goals/selected/yoga/index.rst

@@ -1,9 +0,0 @@
-========
- Yoga
-========
-
-.. toctree::
-   :glob:
-   :maxdepth: 1
-
-   *