Code review of MIL-004: document quoting of values, add RC-019

- Say in the README and config.env.example that a value containing " #"
  must be quoted, and pin both behaviours with a test.
- Say in the script header and the README that details set in config.env
  are not asked.
- Record the review as RC-019 and link it in the traceability matrix.

Task: MIL-004#4
Task: MIL-004#5
Refs #30
Refs #31

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

config.env.example

@@ -35,7 +35,8 @@ GITEA_API_URL=https://<your gitea instance>/api/v1
 # empty. An invalid value stops the run and names the key. Remove or comment
 # out a line to be asked for it. The confirmations ("Create these now" and
 # the questions about existing repositories, directories and files) are
-# always asked.
+# always asked. Put a value that contains " #" in double quotes: an unquoted
+# " #" starts a comment.
 #PROJECT_NAME=my-project
 #PROJECT_DESCRIPTION=What the project is for
 #PROJECT_VISIBILITY=private            # private or public