Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/path_dirname.md

@@ -0,0 +1,40 @@
+---
+title: path dirname
+layout: command
+version: 0.59.0
+---
+
+Get the parent directory of a path
+
+## Signature
+
+```> path dirname --columns --replace --num-levels```
+
+## Parameters
+
+ -  `--columns {table}`: Optionally operate by column path
+ -  `--replace {string}`: Return original path with dirname replaced by this string
+ -  `--num-levels {int}`: Number of directories to walk up
+
+## Examples
+
+Get dirname of a path
+```shell
+> '/home/joe/code/test.txt' | path dirname
+```
+
+Get dirname of a path in a column
+```shell
+> ls ('.' | path expand) | path dirname -c [ name ]
+```
+
+Walk up two levels
+```shell
+> '/home/joe/code/test.txt' | path dirname -n 2
+```
+
+Replace the part that would be returned with a custom path
+```shell
+> '/home/joe/code/test.txt' | path dirname -n 2 -r /home/viking
+```
+