Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/dfr_is-in.md

@@ -0,0 +1,24 @@
+---
+title: dfr is-in
+layout: command
+version: 0.59.0
+---
+
+Checks if elements from a series are contained in right series
+
+## Signature
+
+```> dfr is-in (other)```
+
+## Parameters
+
+ -  `other`: right series
+
+## Examples
+
+Checks if elements from a series are contained in right series
+```shell
+> let other = ([1 3 6] | dfr to-df);
+    [5 6 6 6 8 8 8] | dfr to-df | dfr is-in $other
+```
+