Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/g.md

@@ -0,0 +1,16 @@
+---
+title: g
+layout: command
+version: 0.59.0
+---
+
+Switch to a given shell.
+
+## Signature
+
+```> g (shell-number)```
+
+## Parameters
+
+ -  `shell-number`: shell number to change to
+