Added a logo

[aburrell]

Description

Created a logo and added it to the docs and README.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

Needs PR to test

Test Configuration

• Operating system: OS X Big Sur
• Python version number: (e.g., 3.9)
• Compiler with version number: N/A
• Relevant local setup details: develop

Checklist

• [x] Make sure you are merging into the develop (not main) branch
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] Add a note to Changelog.rst, summarising the changes
• [x] Add yourself to AUTHORS.rst and .zenodo.json

[aburrell]

If you click on the 'details' of the docs/readthedocs.org:apexpy test, and then on the small 'view docs' link to the right of the 'build completed' button (not the big 'view docs' button) you can see the Read the Docs build. This link will also take you there: https://apexpy--118.org.readthedocs.build/en/118/

[ljlamarche]

Excellent, thank you! This looks good to me!