WS symbol in doc unclear

[nabijaczleweli]

The documentation refers to a strings which are

Longer than 22 bytes, but substrings of WS (see below).

and WS is not touched upon anywhere else in the documentation – I'm assuming those are the

Strings consisting of a series of newlines,

But that's really not clear without searching the source for WS.

Present in 0.1.15 and HEAD.