Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/dfr_get-second.md

@@ -0,0 +1,21 @@
+---
+title: dfr get-second
+layout: command
+version: 0.59.0
+---
+
+Gets second from date
+
+## Signature
+
+```> dfr get-second ```
+
+## Examples
+
+Returns second from a date
+```shell
+> let dt = ('2020-08-04T16:39:18+00:00' | into datetime -z 'UTC');
+    let df = ([$dt $dt] | dfr to-df);
+    $df | dfr get-second
+```
+