Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/path_expand.md

@@ -0,0 +1,34 @@
+---
+title: path expand
+layout: command
+version: 0.59.0
+---
+
+Try to expand a path to its absolute form
+
+## Signature
+
+```> path expand --strict --columns```
+
+## Parameters
+
+ -  `--strict`: Throw an error if the path could not be expanded
+ -  `--columns {table}`: Optionally operate by column path
+
+## Examples
+
+Expand an absolute path
+```shell
+> '/home/joe/foo/../bar' | path expand
+```
+
+Expand a path in a column
+```shell
+> ls | path expand -c [ name ]
+```
+
+Expand a relative path
+```shell
+> 'foo/../bar' | path expand
+```
+