This pull request addresses several spelling errors and inconsistencies
in the capitalization of proper nouns within the documentation.
### Motivation and Context
To improve the quality of the documentation, spelling errors and
capitalization mistakes have been corrected. This ensures that the
content is more accurate and easier to read.
### Description
<!-- Describe your changes. -->
Add documentation for installing ORT Extensions on Android and iOS.
Some other minor doc updates.
https://edgchen1.github.io/onnxruntime/docs/extensions/
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Documentation.
