Autogenerate missing docs (#3514)

* Autogenerate missing docs

* Update ansi.md

* Rename question mark command docs

* Delete empty?.md

docs/commands/let-env.md

@@ -0,0 +1,16 @@
+# let-env
+Create an environment variable and give it a value.
+
+## Usage
+```shell
+> let-env <name> <equals> <expr> {flags} 
+ ```
+
+## Parameters
+* `<name>` the name of the environment variable
+* `<equals>` the equals sign
+* `<expr>` the value for the environment variable
+
+## Flags
+* -h, --help: Display this help message
+