Docs: Update documents

Update folder structure in readme to align with build split change.
Specify eRPC test framework in index.rst otherwise it might mislead
users that eRPC test framework is the default one.

Signed-off-by: David Hu <david.hu@arm.com>
Change-Id: I444a4ca97a8b865a9222c4b373c5a758c2822fb0
diff --git a/docs/index.rst b/docs/index.rst
index ca85732..98fb3c2 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -13,7 +13,7 @@
   :titlesonly:
   :hidden:
 
-  Test Framework <tfm_erpc_test_framework>
+  eRPC Test Framework <tfm_erpc_test_framework>
   Test Partitions <tfm_test_partitions_addition>
   Test Suites <tfm_test_suites_addition>