I understand that we have found this "smarter solution" as you desribed above with assembly:single Maven target. In this sense, I'd suggest this change:

" Until we can develop an smarter solution, the recommended installation way is just copying the .jar file to APACHE_FLUME_HOME/plugins.d/cygnus/libext using the cp command :)"

to 

"Thus, to order to install just copy the .jar file to APACHE_FLUME_HOME/plugins.d/cygnus/libext using the cp command."