README improvements for upcoming public announcements

[zhindes]

• This contribution adheres to CONTRIBUTING.md.

What does this Pull Request accomplish?

Improves the README in a few ways.

• Added a table of contents
• Put a link to readthedocs front and center for people who get to the GitHub first (we already have a link to GitHub front and center from readthedocs!)
• Added nidaqmx installdriver to the installation section
• Added a section for Examples
• Minor improvements to readability of the raw rst file

Why should this Pull Request be merged?

New product announcement coming soon is going to highlight our Python API quite a bit.

What testing has been done?

Visual inspection and review of the docs output.

[github-actions]

Test Results

    34 files  ±0      34 suites  ±0   52m 29s ⏱️ +40s
 2 348 tests ±0   1 994 ✅ ±0    354 💤 ±0  0 ❌ ±0 
42 272 runs  ±0  36 020 ✅ ±0  6 252 💤 ±0  0 ❌ ±0 

Results for commit b0eba6e. ± Comparison against base commit 56feb61.

[bkeryan]

Approved with suggestions (spelling)