Add irssi to official images.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <[email protected]> (github: jfrazelle)

library/irssi

@@ -0,0 +1,7 @@
+# maintainer: Jessie Frazelle <[email protected]> (@jfrazelle)
+# maintainer: Tianon Gravi <[email protected]> (@tianon)
+
+0.8.17: git://github.com/jfrazelle/irssi@dfefff246e4a04dee588feafc1d720b5247a112e
+0.8: git://github.com/jfrazelle/irssi@dfefff246e4a04dee588feafc1d720b5247a112e
+0: git://github.com/jfrazelle/irssi@dfefff246e4a04dee588feafc1d720b5247a112e
+latest: git://github.com/jfrazelle/irssi@dfefff246e4a04dee588feafc1d720b5247a112e