jj: Add git commit signing and private commits

Git commits, on push, will be signed by default (just like my git
configuration itself) but *not* every change is signed since that is a
hassle with the working copy technically also being an ever changing
git commit.

Additionally, added a private-commit option which will refuse to push
commits beginning with 'wip: ' to any remote, which is not super useful
for my current use cases but also a nice feature and fun to experiment
with for the future.

vcs/jj/config/sh/alias.d/jj.sh

@@ -23,6 +23,18 @@ js() {
 }
 alias jw="jj show"
 alias jd="jj diff"
+
+# for describe-and-edit workflows
+# https://steveklabnik.github.io/jujutsu-tutorial/real-world-workflows/the-edit-workflow.html
+alias je="jj edit"
+alias jee="jj next --edit"
+
+# for squash-and-go workflows
+# https://steveklabnik.github.io/jujutsu-tutorial/real-world-workflows/the-squash-workflow.html
+alias jss="jj squash"
+alias jsi="jj squash --interactive"
+
+# revset info
 alias jln="jj log -T builtin_log_oneline"
 alias jl="jj log -r '@ | ancestors(trunk()..(visible_heads() & mine()), 3) | trunk()' -T builtin_log_oneline"
 alias jL="jj log -r 'all()'"
@@ -40,13 +52,7 @@ jloof() {
     jj log --patch -r "description($*)"
 }
 
-alias jss="jj squash"
-alias jsi="jj squash --interactive"
-
-alias je="jj edit"
-alias jee="jj next --edit"
-
-# show branches w a couple commits
+# show branches (i.e. head commits) w a couple previous commits
 alias jb="jj log -r 'ancestors(heads(all()), 3)'"
 
 alias jrb="jj rebase"