docs(functions): drop backticks from doc-headers

CONTRIBUTING states doc-headers are written as plain text -- the header
is read as-is by config-help, by funcsave, and by anyone opening the
file, and docs/codespans.py adds the site's inline code spans at render
time. 22 files had drifted from that, carrying 41 hand-written spans
that reached config-help and the man page as literal backtick
characters inside an otherwise verbatim block.

The one span whose content ended in a space is requoted rather than
dropped, so "read> " keeps reading as a prompt string.

functions/__jobrunner_sessions.fish

@@ -5,7 +5,7 @@
 #   __jobrunner_sessions [<tool>]
 #
 # DESCRIPTION
-#   Parses `tmux list-sessions` or `screen -ls` into machine-readable rows,
+#   Parses tmux list-sessions or screen -ls into machine-readable rows,
 #   one per active session: name, PID, state, and start time separated by tabs.
 #   Shared by jobrunner and its completions so both agree on what a session is
 #   named. Prints nothing when no sessions exist.