The plugin directory is nice, but it's still hard to discover plugins that could be relevant. Let's add some metadata about plugins to make it easier to categorize them.

Examples:

• Runtime: nodejs, python, java, N/A. Note that all plugins are written in Node. This is more about whether a plugin is targeted to help a particular runtime, e.g. serverless-python-requirements for packaging Python packages.
• Type: local development, deployment, monitoring. What part of the process does this plugin help with?

Any other categories that could be useful?