Documentation bug in ewa-0.62

[jsmullyan]

For the record: the ewa manual in 0.62 shows backreferences in the rule
configuration language as barewords (without quotes). This actually
doesn't work; they need to be quoted or the rule file won't get lexed
correctly.

I've updated the manual to correct this (and make note of the need to
quote) in SVN and on the website.

Cheers,

js