docs(ngValue) Replace input[select] with option for clarity

Request Type: docs

How to reproduce: 

Component(s): forms

Impact: 

Complexity: small

This issue is related to: 

**Detailed Description:**

It is impossible to create an `input[select]`, so it appears the intention
here was actually `option`.

While `ngOptions` would probably be easier to use in most cases, someone may have a use case for using `ngValue` with `option` which is why I decided to change it in lieu of deleting it, as had been mentioned in the issue.

**Other Comments:**