feat: Added the ability to add custom themes/languages to Shiki (#2518)

* Replaced `shikiTheme` with `shikiConfig`

* Code.astro now accepts custom themes/langs

* Updated docs

* Updated tests

* Fixed language loading

* Added customization examples

* Updated documentation

* Added more tests

* Changelogs

* Changed some spaces to tabs

* Fixed typo in changesets

* Moved tests fixtures

* Rolled back changes to with-markdown-shiki

* Removed lang example in docs

* Optimized Code component

* Try to fix windows errors

* Try to see if this new tests work

1 files changed, 9 insertions, 2 deletions

diff --git a/docs/src/pages/en/guides/markdown-content.md b/docs/src/pages/en/guides/markdown-content.md
index c90c5c1f1..487856171 100644
--- a/docs/src/pages/en/guides/markdown-content.md
+++ b/docs/src/pages/en/guides/markdown-content.md
@@ -97,14 +97,21 @@ export default {
       {
         // Pick a syntax highlighter. Can be 'prism' (default), 'shiki' or false to disable any highlighting.
         syntaxHighlight: 'prism',
-        // If you are using shiki, here you can define a global theme.
-        shikiTheme: 'github-dark',
+        // If you are using shiki, here you can define a global theme and
+        // add custom languages.
+        shikiConfig: {
+          theme: 'github-dark',
+          langs: [],
+          wrap: false,
+        },
       },
     ],
   },
 };
 ```
 
+You can read more about custom Shiki [themes](https://github.com/shikijs/shiki/blob/main/docs/themes.md#loading-theme) and [languages](https://github.com/shikijs/shiki/blob/main/docs/languages.md#supporting-your-own-languages-with-shiki).
+
 ## Markdown Pages
 
 Astro treats any `.md` files inside of the `/src/pages` directory as pages. These files can contain frontmatter, but are otherwise processed as plain markdown files and do not support components. If you're looking to embed rich components in your markdown, take a look at the [Markdown Component](#astros-markdown-component) section.