Add variable labels to `generate_race_var` and `generate_aian_var` programs

[shingtgen]

Is your feature request related to a problem? Please describe.
I noticed the generate_race_var and generate_aian_var programs don't add a variable label, which I think would be helpful (particularly for the aian var, to indicate it's alone or in combination, regardless of Latino ethnicity.) They do add value labels as expected.

Describe the solution you'd like
Add variable label such as "AIAN AOIC, regardless of Latino ethnicity"

Describe alternatives you've considered
I add variable labels myself (not a huge lift)

Additional context
Also noticed the help file for generate_aian_var is missing a word:

In ACS microdata, the variable rac1p [must] exist. In CPS microdata, the variable prdtrace must exist.