Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/str_reverse.md

@@ -0,0 +1,23 @@
+---
+title: str reverse
+layout: command
+version: 0.59.0
+---
+
+outputs the reversals of the strings in the pipeline
+
+## Signature
+
+```> str reverse ...rest```
+
+## Parameters
+
+ -  `...rest`: optionally reverse text by column paths
+
+## Examples
+
+Return the reversals of multiple strings
+```shell
+> 'Nushell' | str reverse
+```
+