Add personalization notes to README

Document that gitconfig user/email/GPG key and the weather alias city
should be updated after cloning.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -171,6 +171,13 @@ The `bin/` directory contains custom git subcommands that are symlinked into `~/
 | `git rebase-on <branch>` | Back up current branch, then pull and rebase onto the given branch |
 | `git rename-branch <old> <new>` | Rename a branch locally and on the remote |
 
+## Personalizing after cloning
+
+A few files contain personal values you'll want to change:
+
+- **`gitconfig`** — update `[user]` name, email, and `signingkey` with your own. If you don't use GPG commit signing, remove the `[commit] gpgsign = true` section and the `signingkey` line.
+- **`zshrc`** — the `weather` alias defaults to Athens, GA. Change it to your city: `alias weather='curl wttr.in/YourCity'`
+
 ## What's included
 
 | File | Purpose |