changes in ci, readme and javadoc

[jeetchoudhary]

CI : Security Fix https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands. The CI will fail if not fixed by 1st June 2023

Readme: the documented goal doesn't exist in makefile anymore

Javadoc: used the ASCII chars instead of chars

[codecov]

Codecov Report

Merging #740 (075350d) into main (b83f53a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main     #740   +/-   ##
=========================================
  Coverage     83.33%   83.33%           
  Complexity      320      320           
=========================================
  Files            26       26           
  Lines          1140     1140           
  Branches        137      137           
=========================================
  Hits            950      950           
  Misses          155      155           
  Partials         35       35           

Impacted Files	Coverage Δ
...esforce/dockerfileimageupdate/utils/RateLimit.java	100.00% <ø> (ø)
...force/dockerfileimageupdate/utils/RateLimiter.java	100.00% <ø> (ø)