docs: move plugins.rst to dev guide section

docs/contributing.rst

@@ -214,6 +214,26 @@ plugins implement the `~letsencrypt.interfaces.IDisplay`
 interface.
 
 
+Writing your own plugin
+=======================
+
+Let's Encrypt client supports dynamic discovery of plugins through the
+`setuptools entry points`_. This way you can, for example, create a
+custom implementation of `~letsencrypt.interfaces.IAuthenticator` or
+the `~letsencrypt.interfaces.IInstaller` without having to merge it
+with the core upstream source code. An example is provided in
+``examples/plugins/`` directory.
+
+.. warning:: Please be aware though that as this client is still in a
+   developer-preview stage, the API may undergo a few changes. If you
+   believe the plugin will be beneficial to the community, please
+   consider submitting a pull request to the repo and we will update
+   it with any necessary API changes.
+
+.. _`setuptools entry points`:
+  https://pythonhosted.org/setuptools/setuptools.html#dynamic-discovery-of-services-and-plugins
+
+
 .. _coding-style:
 
 Coding style

docs/index.rst

@@ -8,7 +8,6 @@ Welcome to the Let's Encrypt client documentation!
    using
    contributing
    packaging
-   plugins
 
 .. toctree::
    :maxdepth: 1

docs/plugins.rst

@@ -1,19 +0,0 @@
-=======
-Plugins
-=======
-
-Let's Encrypt client supports dynamic discovery of plugins through the
-`setuptools entry points`_. This way you can, for example, create a
-custom implementation of `~letsencrypt.interfaces.IAuthenticator` or
-the `~letsencrypt.interfaces.IInstaller` without having to merge it
-with the core upstream source code. An example is provided in
-``examples/plugins/`` directory.
-
-.. warning:: Please be aware though that as this client is still in a
-   developer-preview stage, the API may undergo a few changes. If you
-   believe the plugin will be beneficial to the community, please
-   consider submitting a pull request to the repo and we will update
-   it with any necessary API changes.
-
-.. _`setuptools entry points`:
-  https://pythonhosted.org/setuptools/setuptools.html#dynamic-discovery-of-services-and-plugins