[Feature request] Add a new method of filtering files in the commit message

[zkailong]

Feature

When making a commit, we generally only care about the .md files that we have modified. However, when we modify files, it often causes some plugin configuration files to be modified as well. At this time, if we use {{Files}} as the commit message, the configuration files will also be included in the message. It is hoped that a new function can be added. For example, it would be possible to specify that only .md files are displayed in the commit message (a syntax similar to {{Files:md}} could be used).

Thanks a lot!