Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/str_index-of.md

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+---
+title: str index-of
+layout: command
+version: 0.59.0
+---
+
+Returns starting index of given pattern in string counting from 0. Returns -1 when there are no results.
+
+## Signature
+
+```> str index-of (pattern) ...rest --range --end```
+
+## Parameters
+
+ -  `pattern`: the pattern to find index of
+ -  `...rest`: optionally returns index of pattern in string by column paths
+ -  `--range {any}`: optional start and/or end index
+ -  `--end`: search from the end of the string
+
+## Examples
+
+Returns index of pattern in string
+```shell
+>  'my_library.rb' | str index-of '.rb'
+```
+
+Returns index of pattern in string with start index
+```shell
+>  '.rb.rb' | str index-of '.rb' -r '1,'
+```
+
+Returns index of pattern in string with end index
+```shell
+>  '123456' | str index-of '6' -r ',4'
+```
+
+Returns index of pattern in string with start and end index
+```shell
+>  '123456' | str index-of '3' -r '1,4'
+```
+
+Alternatively you can use this form
+```shell
+>  '123456' | str index-of '3' -r [1 4]
+```
+
+Returns index of pattern in string
+```shell
+>  '/this/is/some/path/file.txt' | str index-of '/' -e
+```
+