fix(docs): strip backticks from Section 5 verbatim EXIT STATUS/ARGUMENTS lines

Section 5 (function manpages) is pandoc-rendered verbatim, so a backtick
there is a literal character on the page, not markup. Nine EXIT STATUS/
ARGUMENTS lines across check_fish_deps, lock, cleanup, claude-pr,
claude-docs, dops, ports, screensleep, and steam-dl quoted a command with
backticks; reworded to plain text matching each function's own DESCRIPTION
style.

Fixes docs/verify-manual.py's test_concat_section_five_stays_verbatim,
failing in CI since before this branch (pre-existing on main, confirmed
against the commit before PR #133 merged).

functions/cleanup.fish

@@ -13,7 +13,7 @@
 #
 # EXIT STATUS
 #   0        No orphans found, or orphans removed successfully
-#   Nonzero  `sudo pacman -Rns` failed
+#   Nonzero  sudo pacman -Rns failed
 #
 # EXAMPLE
 #   cleanup