src/cmd-push-container-manifest: delete inaccurate comment
This file was originally a copy/paste of another file and this comment
was mistakenly left over from that.
Also fix a typo in the sentence above it.
#!/usr/bin/python3
# Push a container manifest (i.e. multi-arch) to a container registry based on
-# arguments provided by ther user.
-
-# The inverse of cmd-buildfetch (i.e. we upload a build which later can be
-# partially re-downloaded with cmd-buildfetch).
+# arguments provided by the user.
import argparse
import os
