Mention `enable: true` when passing object to LR
Mention `enable: true` when passing object to LR

I've realized that setting `filter` property in livereload object is not enough to activate the livereload. The object also needs to set `enable: true` for LR to kick in. Updating readme and adding one more FAQ to make it clear.
sanyueyu/gulp-webserver,schickling/gulp-webserver,bolasblack/gulp-webserver,SteveBash/gulp-webserver,mattraykowski/gulp-webserver,davidknezic/gulp-webserver,robertbaker/gulp-webserver,bialikover/gulp-webserver