Filters (glob, regexp etc.) seemingly cannot contain a space after the colon

[anlutro]

This is either a bug in code or in documentation.

Judging by this documentation, glob: foo-* should be a valid filter.

However, I just spent an hour debugging Flux when the solution turned out to be changing glob: foo-* to glob:foo-*.

I quickly glanced over the code and didn't see any trimming of whitespace going on in pattern.go so I suppose this is just something that snuck into documentation.

It would be nice to support using spaces like this, though.

[circa10a]

@anlutro docs were updated