Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/math_sum.md

@@ -0,0 +1,24 @@
+---
+title: math sum
+layout: command
+version: 0.59.0
+---
+
+Finds the sum of a list of numbers or tables
+
+## Signature
+
+```> math sum ```
+
+## Examples
+
+Sum a list of numbers
+```shell
+> [1 2 3] | math sum
+```
+
+Get the disk usage for the current directory
+```shell
+> ls | get size | math sum
+```
+