docs: Fixing broken links in ReadMe file and minor punctuation

Fixes: N/A

What was the problem/requirement? (What/Why)

I found some links that were broken in the ReadMe file on this package so I'm submitting this PR to fix them.

While I was doing that I decided to proofread the ReadMe file a little bit and decided to fix some minor punctuation/grammar errors, so that everything reads a little better.

What was the solution? (How)

Figured out what were the correct links and fixed them.

What is the impact of this change?

Makes our ReadMe look better. Also less frustration for anyone who was trying to access those links.

How was this change tested?

Not needed. I did ensure that the links were working again and that the formatting looked correct in my own fork.

See DEVELOPMENT.md for information on running tests.

Have you run the unit tests? N/A
Have you run the integration tests? N/A
Have you made changes to the download or asset_sync modules? If so, then it is highly recommended that you ensure that the docker-based unit tests pass.

Was this change documented?

N/A

Are relevant docstrings in the code base updated?N/A
Has the README.md been updated? If you modified CLI arguments, for instance. Yes, this change is updated the ReadMe itself.

Does this PR introduce new dependencies?

N/A

This library is designed to be integrated into third-party applications that have bespoke and customized deployment environments. Adding dependencies will increase the chance of library version conflicts and incompatabilities. Please evaluate the addition of new dependencies. See the Dependencies section of DEVELOPMENT.md for more details.

[ ] This PR adds one or more new dependency Python packages. I acknowledge I have reviewed the considerations for adding dependencies in DEVELOPMENT.md.
[x] This PR does not add any new dependencies.

Is this a breaking change?

N/A

A breaking change is one that modifies a public contract in a way that is not backwards compatible. See the Public Contracts section of the DEVELOPMENT.md for more information on the public contracts.

If so, then please describe the changes that users of this package must make to update their scripts, or Python applications.

Does this change impact security?

N/A

Does the change need to be threat modeled? For example, does it create or modify files/directories that must only be readable by the process owner?
- If so, then please label this pull request with the "security" label. We'll work with you to analyze the threats.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

aws-deadline / deadline-cloud