Update Extramural Reporting README removing NIH approval requirement

<ins>**Proposed Changes**</ins>

**_extramural reporting/README.md_**

1. Clarifying that NIH approval is no longer required.
2. Proofreading
3. Modifying examples to adhere to lowercase alphanumeric requirements

Proposed Labels: **extramural-reporting**, **documentation**

Related PR: https://github.com/microsoft/STRIDES/pull/6