Add drain-retries option to README

[2rs2ts]

It seems like #104 added this option, but since that wasn't yet released, it wasn't added to the README. Now it's part of a release, so, it should be fine to add to the README.

[2rs2ts]

I'm new here. I don't know what I am supposed to do about sign-off on a 1-line commit on the README 😅 no one worked with me on it, so who's there to sign off on it? Myself? Guidance would be appreciated.

[ZihanJiang96]

I'm new here. I don't know what I am supposed to do about sign-off on a 1-line commit on the README 😅 no one worked with me on it, so who's there to sign off on it? Myself? Guidance would be appreciated.

haha just sign it off by yourself
https://github.com/keikoproj/lifecycle-manager/pull/182/checks?check_run_id=20274793558

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (073e30a) 69.78% compared to head (eb39a60) 69.78%.
Report is 1 commits behind head on master.

❗ Current head eb39a60 differs from pull request most recent head 1c82749. Consider uploading reports for the commit 1c82749 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #182   +/-   ##
=======================================
  Coverage   69.78%   69.78%           
=======================================
  Files          12       12           
  Lines        1314     1314           
=======================================
  Hits          917      917           
  Misses        325      325           
  Partials       72       72           

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