feat(docs): Add modules feature page (#2380)

Co-authored-by: Cem Aksoylar <caksoylar@users.noreply.github.com>

docs/docs/development/build-flash.mdx

@@ -108,6 +108,10 @@ west build -b nice_nano -- -DSHIELD=kyria_left -DZMK_CONFIG="C:/Users/myUser/Doc
 The above command must still be invoked from the `zmk/app` directory as noted above, rather than the config directory. Otherwise, you will encounter errors such as `ERROR: source directory "." does not contain a CMakeLists.txt; is this really what you want to build?`. Alternatively you can add the `-s /path/to/zmk/app` flag to your `west` command.
 :::
 
+:::warning
+If your config is also a [module](../features/modules.mdx), then you should also add the root (the folder in which the `zephyr` folder is found) of your `zmk-config` as an [external module to build with](#building-with-external-modules).
+:::
+
 In order to make your `zmk-config` folder available when building within the VSCode Remote Container, you need to create a docker volume named `zmk-config`
 by binding it to the full path of your config directory. If you have run the VSCode Remote Container before, it is likely that docker has created this
 volume automatically -- we need to delete the default volume before binding it to the correct path. Follow the following steps:

docs/docs/development/new-shield.mdx

@@ -51,6 +51,13 @@ Follow these steps to create your new repository:
   - Select Public or Private, depending on your preference.
 - Click the green "Create repository" button
 
+The repository is a combination of the directories and files required of a ZMK config, and those required of a shield module. To create a shield module, the following components are needed:
+
+- The `boards/shields` directory, where the keyboard's files will go
+- The `zephyr/module.yml` file, which identifies and describes the module. See the [Zephyr documentation](https://docs.zephyrproject.org/3.5.0/develop/modules.html#module-yaml-file-description) for details on customising this file. For the purposes of creating a shield module, the default found in the template can be left untouched.
+
+Neither of these should be moved out of their parent directory. The other files and directories such as `config` are not necessary for the purposes of a shield module, but rather intended to be used for user configuration and testing.
+
 ## New Shield Directory
 
 :::note