Adding full list of subscription options in docs and types

[tsekiguchi]

I've been digging through the docs to find what fields are available for me to query when setting up subscription options. However, in the subscription command page, there is no mention of what a full list of options is.

The types that are included in fb-watchman are painfully lacking, and need to be updated. For example, in the NodeJS docs page, in "Initiating a watch", the comments say that "is very important to record the relative_pathreturned in resp".

However, resp.relative_path returns undefined and doesn't even exist on the resp object.

For a package that is downloaded almost 20m times weekly, I would hope to help all future users understand the options available through updating both the docs and types. If the information is provided, I'm happy to assist with generating types, etc.