Correct Typo in CoreNet's and OpenELM's Documentation

[aakashapoorv]

In the Model Implementations section of the Directory Structure, I've made the following correction:

From	To
moels	models

In OpenELM Documentation, I've made the following correction:

From	To
LLamav1/v2	LLama v1/v2

[aakashapoorv]

Added changes from https://github.com/apple/corenet/pull/8 as well