RESP3 connection examples

[chayim]

As part of adding support for RESP3 in 5.x we need to communicate to our users how to enable RESP 3. This PR contains three items:

1. A basic example for the README

2. Updates to the sync examples, to share a redis_url style connection, as well as a basic connection, with RESP3

3. An async example highlighting the protocol=3 usage with async.

While here, I modified the async examples to include a URL based connection example, as one was missing

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.04% ⚠️

Comparison is base (2732a85) 90.66% compared to head (19eac07) 90.63%.

❗ Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2863      +/-   ##
==========================================
- Coverage   90.66%   90.63%   -0.04%     
==========================================
  Files         126      126              
  Lines       32229    32229              
==========================================
- Hits        29221    29210      -11     
- Misses       3008     3019      +11     

see 7 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[chayim]

needs #2869 at least