Change to git add renormalize command after changing line endings

[mems]

Why:

I follow the instructions of "Refreshing a repository after changing line endings", but after normalize all files in a repo, some files still unnormalized (when I switch branches or merge, these "fantom-changes-that-can't-be-undo" appears).
After few search on the web, I found the mentioned command (git rm -rf --cached . ; git reset --hard HEAD) aren't recommended in git doc, but git add --renormalize . is since git 2.16 ("a new and safer way to record the fact that you are correcting the end-of-line convention").
Before it was use different command combinations:

• git/git@9472935#diff-8c2ad6307733b92b3f5a6a70a3f3bbe1076c0fdf4da66c3633f90d15c6cf118aL235
• git/git@773a889#diff-8c2ad6307733b92b3f5a6a70a3f3bbe1076c0fdf4da66c3633f90d15c6cf118aL232
• git/git@8599974#diff-8c2ad6307733b92b3f5a6a70a3f3bbe1076c0fdf4da66c3633f90d15c6cf118aL230
• git/git@fd6cce9#diff-8c2ad6307733b92b3f5a6a70a3f3bbe1076c0fdf4da66c3633f90d15c6cf118aR209

What's being changed (if available, include any code snippets, screenshots, or gifs):

Change the snippet to use the command that normalize all files

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require a SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing.

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[nguyenalex836]

@mems Thanks so much for opening a PR! I'll get this triaged for review ✨