docs: add api description for orbitdb.open

API.md

@@ -291,7 +291,19 @@ const db = await orbitdb.create('user.posts', 'eventlog', {
 })
 // db created & opened
 ```
-### orbitdb.open(name|address, [options])
+### orbitdb.open(address, [options])
+> Opens an OrbitDB database.
+
+Convienance methods are available when opening/creating any of the default OrbitDB database types (i.e. `orbitdb.feed(address, options)` instead of `orbitdb.open(address, { type: 'feed', ... })`)
+
+Returns a `Promise` that resolves to [a database instance](#store). `address` (string) should be a valid OrbitDB address. If a database name is provided instead, it will check `options.create` to determine if it should create the database. `options` is an object with any of the following properties:
+
+- `localOnly` (boolean): If set to `true`, will throw an error if the database can't be found locally. (Default: `false`)
+- `directory` (string): The directory where data will be stored (Default: uses directory option passed to OrbitDB constructor or `./orbitdb` if none was provided).
+- `create` (boolean): Whether to create the database if a valid OrbitDB address is not provided. (Default: `false`)
+- `type` (string): A supported database type (i.e. `eventlog` or [an added custom type](https://github.com/orbitdb/orbit-db#custom-store-types)). Required if create is set to `true`. Otherwise it's used to validate the manifest.
+- `overwrite` (boolean): Overwrite an existing database (Default: `false`)
+
 ### orbitdb.stop()
 
   Stop OrbitDB, close databases and disconnect the databases from the network.