Add PPA build instructions

Author: oschwald

README.dev.md

@@ -0,0 +1,15 @@
+Current PPA process:
+
+1. Make an upstream/2.x.y branch off of the v2.x.y tag.
+2. git co ubuntu-ppa
+3. git merge v2.x.y
+4. dch -i
+  * Add new entry for utopic. Follow existing PPA versioning style.
+5. Ensure your checkout is really clean. This includes ignored files. Our debian
+   build does not currently ignore them.
+6. gbp buildpackage -S
+7. dput ppa:maxmind/ppa ../geoipupdate_<TAG>-<DEB VERSION>_source.changes
+
+If 7 was successful, modify debian/changelog and repeate 6 & 7 for trusty and
+precise.
+