docs: change note, and warning syntax

Changed syntax for `note` and `warning` as mkdocs does not support it. I will
later try to enable the original github markdown syntax.

Author: Tygo-van-den-Hurk

docs/index.md

@@ -35,8 +35,8 @@ There are several ways to install Slyde: [installing an npm package](#npm-packag
 
 ### NPM package installation
 
-> [!NOTE]
-> This might require a token from GitHub to function.
+NOTE:
+This might require a token from GitHub to function.
 
 To install Slyde using npm from [GitHub' NPM registry](https://npm.pkg.github.com/), run the following command:
 
@@ -56,8 +56,8 @@ docker run --volume "$PWD:/src" --rm ghcr.io/tygo-van-den-hurk/slyde:latest comp
 
 ### Building from source
 
-> [!WARNING]
-> This option is not recommended even if you chose to install `--global` as this makes your system harder to replicate. The previous options are recommended for almost all use cases.
+WARNING:
+This option is not recommended even if you chose to install `--global` as this makes your system harder to replicate. The previous options are recommended for almost all use cases.
 
 You can install slyde as a dependency to your project, run the following commands: