feat: adjust git doc

doc/alpine-git.md

@@ -0,0 +1,27 @@
+# Setup Git
+
+* update your APT cache using
+```
+doas apk update
+```
+
+* install Git from Debian's APT repository
+```
+doas apk add git
+```
+
+* verify installation
+```
+git --version
+```
+
+* provide contact details to be embedded in the commit message
+```
+git config --global user.name "<tbd>"
+git config --global user.email "<tbd>"
+```
+
+* verify contact details
+```
+git config --list
+```