docs(functions): merge remaining manual prose into function headers

Folds the last seven manual entries whose description exceeded their header
back into the source-of-truth comment blocks: config-settings (Sponge/Paths
page detail, list-value parsing, width tiers, navigation keys), fish-deps
(install-method priority, dependency tiers), logs (fzf keybindings, ov
viewer behavior), kitty-logging (symlink wording, C5 inert-vs-uninstalled),
config-update (exec fish reload), yt-dlp (C1 guard). Drops duplicate example
lines left by the previous merge.

functions/config-update.fish

@@ -13,7 +13,7 @@
 #   The remote URL is hard-coded so the update works even if the local clone
 #   has no configured remote. Git output is suppressed; status is reported
 #   through colored messages. After a successful pull the function prints a
-#   short summary of changed files.
+#   short summary of changed files; run `exec fish` to reload the shell.
 #
 # ARGUMENTS
 #   -h, --help      Show this help message and exit