Add example on how to implement branch name completion for hg update/hg merge

Examples-(completion).md

@@ -66,3 +66,24 @@ _fzf_complete_pass() {
 
 [ -n "$BASH" ] && complete -F _fzf_complete_pass -o default -o bashdefault pass
 ```
+
+### Complete hg update/hg merge
+
+If you need to add branch name completion for a subset of hg commands, e.g. hg up, hg merge, you can use technique as follows (zsh completion):
+
+```sh
+_fzf_complete_hg() {
+  ARGS="$@"
+  if [[ $ARGS == 'hg merge'* ]] || [[ $ARGS == 'hg up'* ]]; then
+    _fzf_complete "--no-sort" "$@" < <(
+      { hg branches & hg tags }
+    )
+  else
+    eval "zle ${fzf_default_completion:-expand-or-complete}"
+  fi
+}
+
+_fzf_complete_hg_post() {
+  cut -f1 -d' '
+}
+```