Update README.md

update cordova hello world link to https://github.com/apache/cordova-app-hello-world
[#43] Guidance added to config.xml
[#43] Reformat the config.xml comments.
[#43] Use current version of PhoneGap.
Updated for Rev. 8 instead of 14
Changed Android minSDK to 8 since this corresponds to more phones and will help beginners get their programs going sooner.
Changed to v7 for Android to match https://build.phonegap.com/docs/config-xml minimum
Update from apache/cordova-app-hello-world
Use PhoneGap 2.5.0
fixed typo in comment

also, the comment says "allow any secure requests" but the example URL isn't HTTPS -- not sure if this is correct