Remove dev and main branch from workflows. (#404)

* Remove `dev` and `main` branch from workflows.

Update links in documentation.

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

* `amd-staging` -> `amd-mainline` in docs

Signed-off-by: Peter Jun Park <peter.park@amd.com>

---------

Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Signed-off-by: Peter Jun Park <peter.park@amd.com>
Co-authored-by: Peter Jun Park <peter.park@amd.com>

.github/workflows/tarball.yml

@@ -2,7 +2,7 @@ name: tarball
 
 on:
   push:
-    branches: [ main, amd-mainline ]
+    branches: [ amd-mainline ]
   pull_request:
 
 concurrency: