feat: add edit this post link

[kungfux]

Type of change

• New feature (non-breaking change which adds functionality)

Description

Add "Edit this post" link at the bottom of the post, so it is easier for users to contibute to the blog content.
The feature is disabled by default and should be enabled and configured by editing _data/edit-this-post.yml.

Additional context

Closes #2067

Demo

[cotes2020]

Thanks! This seems like an interesting feature, but blog and documentation websites have different purposes. Most people wouldn't invite others to modify their posts, so the priority for implementing this feature isn't very urgent.

The current PR design, placing new links at the bottom of posts, looks a bit cluttered. I plan to revisit this feature once I have time to think of a cleaner UI layout.

[kungfux]

Thanks! I mainly wanted to experiment with implementing this feature since there was a request for it. I completely agree with your points, the feature definitely needs some refinement, as you mentioned. I also understand that people might use the theme differently from what was originally intended, so it could still be useful in some cases. Anyway, I'll rely on your decision regarding how to proceed. No hard feelings 😀

[cotes2020]

Sorry for losing track of this PR. Let's go ahead with the current implementation for now—things are rarely perfect on the first try, and we can always iterate on the UI later. One point worth discussing, though: would it be better to move the configuration options to _config.yml?