Selectively cleaning git history

This way we clean any unwanted commits from the git history.

Requires: Java, bfg-repo-cleaner

1. First create a local copy of the repo folder (as backup just in case)

2. Clone a mirror of the git repo to a new location.

   git clone --mirror git@github.com:gqc/IoT_Arduino_to_ESP-IDF.git

3. Clean up the repo as desired.
   In my case, I wanted to clean a build directory that was uploaded in an earlier commit.
   Check this for more usage commands.

   java -jar bfg-1.14.0.jar --delete-folders build IoT_Arduino_to_ESP-IDF.git

4. Go into the repo directory and commit the changes

   cd IoT_Arduino_to_ESP-IDF.git
   
   git reflog expire --expire=now --all && git gc --prune=now --aggressive

5. Push the changes to github

   git push

6. Delete the mirror and the old repo you had. Clone a fresh copy of the repo from github. Make sure to compare with the backup you created in the step 1 and that haven't missed any important files in the cleaning step.