Add useful global git configuration

tools/git-setup.md

@@ -3,14 +3,32 @@
 
 ## Tell git who you are
 
-```
+```bash
 $ git config --global user.name 'Jean R. Hacker'
 $ git config --global user.email 'jean@agaric.com'
 ```
 
+## Align on some basics
+
+Have same default branch, pull settings, and ability to see vault diffs as other Agarics.
+
+```bash
+git config --global init.defaultBranch main
+git config --global pull.ff only
+git config --global diff.ansible-vault.textconv "ansible-vault view"
+```
+
+## Let Git's git clean fully clean out (optional)
+
+This one's a little dangerous, but use `git clean` carefully and appreciate not having to manually delete unwanted local files. 
+
+```bash
+git config --global clean.requireForce false
+```
+
 ## Create a personal excludesfile (optional)
 
-```
+```bash
 $ touch ~/.gitignore
 $ git config --global core.excludesfile ~/.gitignore
 ```