Update docs (cortexlabs#2128)

(cherry picked from commit 5998c35)

Add tags without hostnames to images

(cherry picked from commit 2db1df8)

Docs for Realtime gRPC (cortexlabs#2018)

(cherry picked from commit b8ac916)

Update stable version to 0.31.1

Docs for multi-instance type clusters (cortexlabs#1968)

(cherry picked from commit fce0df9)

Auth and logging docs nits (cortexlabs#1931)

(cherry picked from commit 0f1b6b1)

Update version to 0.29.0

Provide default bucket name if bucket is not set (cortexlabs#1855)

(cherry picked from commit 7e08141)

Update version to 0.27.0

Update version to 0.26.0