Add giscus support (#3022)

* Add script in same style as utterances

But adjusted for the various filed differences

* Add initial script

* Add default settings

* Update changelog

* Add feature to readme

* Add comments html

* add comment provider include

* update config in docs

* Add URL for additional reference

* docs for giscus comments

* Unrelated bugfix: add missing version separator

So that things match the "history" doc.

* add space

* update history doc

* update about doc

* add to test config yaml

* remove unnecessary / incorrect async attribute

* probably should pass the right config paths

* lowercase the repo name

* Update docs to address '1' and '0' for reactions_enabled

Figured I'd match the giscus format rather than convert a boolean to an int there.

* update two additional docs

* docs wording fix

docs/_docs/05-configuration.md

@@ -333,7 +333,7 @@ For example,
 
 ### Comments
 
-[**Disqus**](https://disqus.com/), [**Discourse**](https://www.discourse.org/), [**Facebook**](https://developers.facebook.com/docs/plugins/comments), [**utterances**](https://utteranc.es/), and static-based commenting via [**Staticman**](https://staticman.net/) are built into the theme. First set the comment provider you'd like to use:
+[**Disqus**](https://disqus.com/), [**Discourse**](https://www.discourse.org/), [**Facebook**](https://developers.facebook.com/docs/plugins/comments), [**utterances**](https://utteranc.es/), [**giscus**](https://giscus.app/) and static-based commenting via [**Staticman**](https://staticman.net/) are built into the theme. First set the comment provider you'd like to use:
 
 | Name             | Comment Provider          |
 | ---------------- | ------------------------- |
@@ -343,6 +343,7 @@ For example,
 | **staticman_v2** | Staticman v2 / v3         |
 | **staticman**    | Staticman v1 (deprecated) |
 | **utterances**   | utterances                |
+| **giscus**       | giscus                    |
 | **custom**       | Other                     |
 
 Then add `comments: true` to each document you want comments visible on.
@@ -424,6 +425,35 @@ comments:
     issue_term: "pathname"
 ```
 
+#### giscus comments
+
+To use giscus you will need to [install the app](https://github.com/apps/giscus) to your GitHub repository.
+
+The next step is to go to <https://giscus.app> and fill out the desired settings. This will generate JavaScript that will provide you with the settings you will need to configure things below.
+
+You'll need to ensure you've added the following to `_config.yml`:
+
+```yaml
+repository: # GitHub username/repo-name e.g. "mmistakes/minimal-mistakes"
+```
+
+**Note:** Make sure the repo is public, otherwise your readers will not be able to view the issues/comments. The [discussions feature](https://docs.github.com/en/discussions) also needs to be active on your repo.
+{: .notice--warning}
+
+To enable giscus on the front end set `comments.provider` and the other additional options.
+
+```yaml
+comments:
+  provider: "giscus"
+  giscus:
+    repo_id              : # Shown during giscus setup at https://giscus.app
+    category_name        : # Full text name of the category
+    category_id          : # Shown during giscus setup at https://giscus.app
+    discussion_term      : # "pathname" (default), "url", "title", "og:title"
+    reactions_enabled    : # '1' for enabled (default), '0' for disabled
+    theme                : # "light" (default), "dark", "dark_dimmed", "transparent_dark", "preferred_color_scheme"
+```
+
 #### Static-based comments via Staticman
 
 Transform user comments into `_data` files that live inside of your GitHub repository by enabling Staticman.

docs/_docs/18-history.md

@@ -24,6 +24,8 @@ toc: false
 - Remove `h2` from skip links navigation as it is not important for site structure. [#3012](https://github.com/mmistakes/minimal-mistakes/pull/3012)
 - Loads Font Awesome asynchronously. [#2967](https://github.com/mmistakes/minimal-mistakes/pull/2967)
 - Replace custom search icon SVG with Font Awesome icon. [#2774](https://github.com/mmistakes/minimal-mistakes/pull/2774)
+- Adds support for giscus comments. [#3022](https://github.com/mmistakes/minimal-mistakes/pull/3022)
+
 ## [4.23.0](https://github.com/mmistakes/minimal-mistakes/releases/tag/4.23.0)
 
 ### Enhancements