Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/str_contains.md

@@ -0,0 +1,50 @@
+---
+title: str contains
+layout: command
+version: 0.59.0
+---
+
+Checks if string contains pattern
+
+## Signature
+
+```> str contains (pattern) ...rest --insensitive```
+
+## Parameters
+
+ -  `pattern`: the pattern to find
+ -  `...rest`: optionally check if string contains pattern by column paths
+ -  `--insensitive`: search is case insensitive
+
+## Examples
+
+Check if string contains pattern
+```shell
+> 'my_library.rb' | str contains '.rb'
+```
+
+Check if string contains pattern case insensitive
+```shell
+> 'my_library.rb' | str contains -i '.RB'
+```
+
+Check if string contains pattern in a table
+```shell
+>  [[ColA ColB]; [test 100]] | str contains 'e' ColA
+```
+
+Check if string contains pattern in a table
+```shell
+>  [[ColA ColB]; [test 100]] | str contains -i 'E' ColA
+```
+
+Check if string contains pattern in a table
+```shell
+>  [[ColA ColB]; [test hello]] | str contains 'e' ColA ColB
+```
+
+Check if string contains pattern
+```shell
+> 'hello' | str contains 'banana'
+```
+