Prep work for branch renaming (ROCm#389)

* Add `amd-staging` and `amd-mainline` to workflow.
* Update branch names in documentation
* Change `dev` to `amd-staging` and `main` to `amd-mainline` in documentation.
* Remove references from 2.x from workflows.
* Convert the link to LICENSE to a relative path in CONTRIBUTING.

---------

Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Signed-off-by: xuchen-amd <xuchen@amd.com>

.github/workflows/docs.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Build 1.x docs
         run: |
           cd docs/archive/docs-1.x
-          make html	
+          make html
       - name: Build 2.x docs
         run: |
           cd docs/archive/docs-2.x

CONTRIBUTING.md

@@ -31,11 +31,7 @@ and apply your changes there.
 
 - Ensure the PR description clearly describes the problem and solution. If there is an existing GitHub issue open describing this bug, please include it in the description so we can close it.
 
-<<<<<<< HEAD
-- Ensure the PR is based on the `amd-staging` branch of the ROCm Compute Profiler GitHub repository.
-=======
-- Ensure the PR is based on the `dev` branch of the ROCm Compute Profiler GitHub repository.
->>>>>>> 1939361b (Rebranding of top level md files.)
+- Ensure the PR is based on the `amd-staging` branch of the Omniperf GitHub repository.
 
 - ROCm Compute Profiler requires new commits to include a "Signed-off-by" token in the commit message (typically enabled via the `git commit -s` option), indicating your agreement to the projects's [Developer's Certificate of Origin](https://developercertificate.org/) and compatability with the project [LICENSE](LICENSE):