index.md: Update docs to align with the latest tf-m-ci-scripts

This patch makes the following updates:
1. Update the link of tf-m-ci-scripts from TF-Mv1.7.0 to TF-Mv1.8.0 tag.
2. Update description in TF-M CI scripts overview to align with the
latest change to decouple regression tests control on BL2, Secure and
Non-Secure.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I9c727c9070917ddcfccb5ebf3ba3ac0d99cc5379
1 file changed
tree: 766cee5d94b8e30aa4eea3629d8ddf3fab4ff7e5
  1. docs/
  2. .gitreview
  3. mkdocs.yml
  4. requirements.txt