Also fixes links to section headings that
have changed.

Many code blocks are 4spaced, and they render in GitLab
without coloring as a result, even though they are
fenced with a language label. If in a list, other items
woll render as being in a code block too, even if not
meant to. This fixes all these issues, and cleans up
minor whitespace issues in /user, /security, /ssh
and /migrate_ci_to_ce docs.

GitLab uses a kubernetes service account to perform deployments. For
serverless deployments to work as expected with externally created
clusters with their own knative installations (e.g. via Cloud Run), this
account requires additional permissions in the serving.knative.dev API
group.

This reverts commit 092542d2fa5c036e4fc01ba3185f1dc0e9ddbebb.

Included a stray file

Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>

For the sake of consistency, removes any extraneous
consecutive blank lines from the doc suite.