Improve readability of cloak request section

Improve readability of cloak request section

The "drop in(to)" idiom may confuse non-native / newer users of English, and the spelling here makes it look as if "to" is used as an infinitive (rather than using the preposition "into"), which may exacerbate this confusion.

This PR changes the grammar to be both more direct about the action the user should take, and more consistent with IRC-related terminology. Since the paragraph had to be reflowed for 80 columns, the actual change is:

"please drop in to #freenode" -> "please join the #freenode channel"