Add explanatory comment to build-deb
Add explanatory comment to build-deb

This is just adding a little comment to clarify the usage of this
script: What needs to be installed for it to run, and where it puts the
packages after.

wiltonlazary/arangodb,Simran-B/arangodb,graetzer/arangodb,Simran-B/arangodb,arangodb/arangodb,arangodb/arangodb,fceller/arangodb,hkernbach/arangodb,Simran-B/arangodb,wiltonlazary/arangodb,fceller/arangodb,hkernbach/arangodb,graetzer/arangodb,hkernbach/arangodb,joerg84/arangodb,graetzer/arangodb,Simran-B/arangodb,graetzer/arangodb,arangodb/arangodb,arangodb/arangodb,hkernbach/arangodb,hkernbach/arangodb,fceller/arangodb,joerg84/arangodb,joerg84/arangodb,joerg84/arangodb,Simran-B/arangodb,hkernbach/arangodb,wiltonlazary/arangodb,joerg84/arangodb,wiltonlazary/arangodb,arangodb/arangodb,fceller/arangodb,graetzer/arangodb,graetzer/arangodb,joerg84/arangodb,Simran-B/arangodb,Simran-B/arangodb,wiltonlazary/arangodb,fceller/arangodb,graetzer/arangodb,hkernbach/arangodb,graetzer/arangodb,hkernbach/arangodb,graetzer/arangodb,hkernbach/arangodb,fceller/arangodb,joerg84/arangodb,graetzer/arangodb,joerg84/arangodb,hkernbach/arangodb,fceller/arangodb,hkernbach/arangodb,joerg84/arangodb,joerg84/arangodb,arangodb/arangodb,hkernbach/arangodb,joerg84/arangodb,arangodb/arangodb,wiltonlazary/arangodb,fceller/arangodb,hkernbach/arangodb,joerg84/arangodb,arangodb/arangodb,hkernbach/arangodb,joerg84/arangodb,fceller/arangodb,joerg84/arangodb,graetzer/arangodb,Simran-B/arangodb,Simran-B/arangodb,wiltonlazary/arangodb,graetzer/arangodb,wiltonlazary/arangodb,fceller/arangodb,graetzer/arangodb,graetzer/arangodb,Simran-B/arangodb