docs: Correct trailing spaces in markdown files and add .editorconfig instruction file

[DannyvdSluijs]

Description

This PR combines #869, #868, #867 and #866

Related Issue

Replaces #869, #868, #867 and #866

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Other (please describe):

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the code style of this project
• I have added tests that prove my fix is effective or that my feature works
• All new and existing tests pass
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional Notes

This PR is credited to @reedy who discovered the trailing spaces