Auto-generate markdown command docs (#4451)

* Finish updating

* a couple improvements

* Update renames

* cleanup examples

docs/commands/dfr_sample.md

@@ -0,0 +1,30 @@
+---
+title: dfr sample
+layout: command
+version: 0.59.0
+---
+
+Create sample dataframe
+
+## Signature
+
+```> dfr sample --n-rows --fraction --replace```
+
+## Parameters
+
+ -  `--n-rows {int}`: number of rows to be taken from dataframe
+ -  `--fraction {number}`: fraction of dataframe to be taken
+ -  `--replace`: sample with replace
+
+## Examples
+
+Sample rows from dataframe
+```shell
+> [[a b]; [1 2] [3 4]] | dfr to-df | dfr sample -n 1
+```
+
+Shows sample row using fraction and replace
+```shell
+> [[a b]; [1 2] [3 4] [5 6]] | dfr to-df | dfr sample -f 0.5 -e
+```
+