createMessage: docs incorrectly list "Array of strings" as parameter

[dmackca]

(This is for v0.13.3, the latest release on npm as of this post; btw the docs on the website say they're for 0.13.2 in the title tag)

The Client.createMessage function in the docs says the content parameter can be:

String | Array | Object
A string, array of strings, or object. [...]

I wondered if an array of strings might send a random one, but it actually just throws this error:

No content, file, or embed

It doesn't look like there's anything in the code to check or handle arrays of strings here, but it's mentioned in the comments:

eris/lib/Client.js

Line 1067 in 6d4668c

* @arg {String | Array | Object} content A string, array of strings, or object. If an object is passed:

[bsian03]

Will fix this in #993