solve the issue #670 Configure similarity index for diffs

[x13machine]

Thank you for taking the time to contribute to GitLens! ♥

Description

Solves issue #670.

• specifies the -M{x}% parameter in git diff when comparing
• adds setting gitlens.views.compare.findRenames
• adds info about the settings in README.md

Checklist

• I have followed the guidelines in the Contributing document
• My changes are based off of the develop branch
• My changes follow the coding style of this project
• My changes build without any errors or warnings
• My changes have been formatted and linted
• My changes include any required corresponding changes to the documentation
• My changes have been rebased and squashed to the minimal number (typically 1) of relevant commits
• My changes have a descriptive commit message with a short title, including a Fixes $XXX - or Closes #XXX - prefix to auto-close the issue that your PR addresses

[eamodio]

@x13machine Thank you for your contribution! Can you please remove all the formatting changes? Otherwise I can't tell what are required changes vs formatting issues. Thanks!

[x13machine]

ok I think, I fixed it.

[eamodio]

@x13machine Thank you so much for your contribution!!