feat: allow per-page description customization

[meysam81]

Hello @Guts

Thanks for the awesome project.

I use this plugin heavily in my SRE blog.

I figured it would be nice to allow per page customization of the description field, cause at the moment, there's not a lot one can do when the description before <!-- more --> is short and extra detail is desired.

With this change, you can have separate contents for RSS description and your typical content.

An example taken from the Material for Mkdocs Social Cards:

---
date: 2024-06-24
description: >-
  This is the SEO description.
social:
  cards_layout_options:
    description: >-
      This is the social cards description.
rss:
  feed_description: >-
    And I want to have customized RSS description.
---

This idea, I reckon, can easily be extended for other similar use-cases:

• New feature: easily customisable jinja2 templates per-feed? #297
• Multiple authors / RSS email #275
• Question: Per item image in page.meta.image with relative path #197

[Guts]

Hi @meysam81 ,

Thanks for your PR. I'm still thinking if it's worth it because it adds a certain complexity from an operational point of view, with nesting levels that are difficult to track and debug.

Remarks:

• can you explain why the description is not enough for your need?
• since it adds something a bit hard to understand and kind of complexity, can you write a documentation more extensive? Maybe a subsection How to customize feed 's item description per page with a different
• can you comply with contributing guidelines and add tests cases please? It does really matter for the project maintainability.

[meysam81]

can you explain why the description is not enough for your need?

description is used for SEO description and in order to optimize it, you'd normally keep it short in around 140-156 characters.
RSS description, however, can go a little wild in the length and doesn't have to comply with anything, especially knowing that it will provide more context to the RSS clients before clicking on Continue reading....

I will add the docs and the tests later this week.

Thanks for the feedback.

[meysam81]

@Guts

Please have another look and let me know if there's any other change required.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.70%. Comparing base (c62cb56) to head (6506bae).

Additional details and impacted files

@@            Coverage Diff             @@
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+ Coverage   80.64%   80.70%   +0.05%     
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  Files          10       10              
  Lines         651      653       +2     
  Branches      133      134       +1     
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+ Hits          525      527       +2     
  Misses         86       86              
  Partials       40       40              

Flag	Coverage Δ
unittests	80.55% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
mkdocs_rss_plugin/util.py	73.52% <100.00%> (+0.19%)	⬆️

[Guts]

LGTM 🚀!

Thanks a lot for your contribution!

[Guts]

Released as part of https://github.com/Guts/mkdocs-rss-plugin/releases/tag/1.15.0