Update README.md - add Docs badge and link License badge to license file

[kdpsingh]

Overview

• The documentation is linked at the top-right of the repository page but not within the README itself
• The License badge, when clicked, points to the image of the badge rather than the text of the license

Description of changes

• Adds a documentation badge to the front of the README to make it easy to find
• Points the License badge to the License.txt file within the repository

Author Checklist

• Happy to update the changelog but since the changes only affect the README, not sure if needed

• [N/A] Linting passes; run early with pre-commit hook.

• [N/A] Tests added for new code and issue being fixed.

• [N/A] Added type annotations and full numpy-style docstrings for new methods.

• [Needed?] Draft your news fragment in new changelog/ISSUE.TYPE.rst files; see changelog/README.md.

[diehlbw]

Also, don't worry about the changelog check failing. That is my fault, and an issue I'll write up.
Currently, labels only seem to be checked at time of commit so it isn't skipping that properly.

I agree this shouldn't necessitate that update

[CLAassistant]

All committers have signed the CLA.