Add docs for how to add a new instrumentation/plugin
# Agent Plugins
This folder contains agent plugins.
-A plugin most of the time is an instrumentation for a specific framework or technology.
+A plugin most commonly is an instrumentation for a specific framework or technology.
+To add a new plugin,
+follow these steps:
+
+1. Create a new maven sub-module in `apm-agent-plugins`
+1. Add the module in the `<modules>` section of [`apm-agent-plugins/pom.xml`](pom.xml)
+1. Add a dependency to your new module in `elastic-apm-agent/pom.xml` to make sure it is included in the agent jar
+1. If you need to add any new runtime dependencies for the agent, make sure to properly configure shading in
+ [`elastic-apm-agent/pom.xml`](../elastic-apm-agent/pom.xml)
+1. Properly test your module with unit tests and consider adding integration tests.
+ See [`CONTRIBUTING.md`](../CONTRIBUTING.md#coding-guidelines) for more guidance.
+1. Add information about the supported technology in [`docs/intro.asciidoc`](../docs/intro.asciidoc)
+1. Add a line in [`CHANGELOG.md`](../CHANGELOG.md)
+
-If you want to add a plugin,
-don't forget to add it as a dependency to apm-agent-java
