docs(functions): merge manual-only examples and notes into headers

Folds the examples Section 5 carried but the headers did not into each
function's `# EXAMPLE`, and moves the three lines that only looked like
examples -- the two typo-abbreviation notes and rm's /usr/bin/rm fallback --
into `# NOTES`, the label already in use.

Also corrects gi's synopsis, which omitted -l, and documents yt-dlp's
--no-embed-thumbnail in `# ARGUMENTS`.

functions/repo-open.fish

@@ -42,6 +42,12 @@
 #   repo-open              # open current branch (+ subdir) in browser
 #   repo-open --print      # just print the URL
 #   repo-open --root       # repo home page for the current branch
+#   repo-open
+#   repo-open --print
+#   repo-open --root
+#
+# NOTES
+#   Typo abbreviation: open-repo (expands to repo-open on space/enter).
 function repo-open --description 'Open the origin remote of the current repo in a browser'
     argparse -X 0 h/help p/print r/root -- $argv
     or return 1