Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/str_find-replace.md

@@ -0,0 +1,36 @@
+---
+title: str find-replace
+layout: command
+version: 0.59.0
+---
+
+finds and replaces text
+
+## Signature
+
+```> str find-replace (find) (replace) ...rest --all```
+
+## Parameters
+
+ -  `find`: the pattern to find
+ -  `replace`: the replacement pattern
+ -  `...rest`: optionally find and replace text by column paths
+ -  `--all`: replace all occurrences of find string
+
+## Examples
+
+Find and replace contents with capture group
+```shell
+> 'my_library.rb' | str find-replace '(.+).rb' '$1.nu'
+```
+
+Find and replace all occurrences of find string
+```shell
+> 'abc abc abc' | str find-replace -a 'b' 'z'
+```
+
+Find and replace all occurrences of find string in table
+```shell
+> [[ColA ColB ColC]; [abc abc ads]] | str find-replace -a 'b' 'z' ColA ColC
+```
+