added usage information to contrib

full usage information:
usage: contrib [feature | hotfix] [start | submit | delete]

context-specific usage information for features:
usage: contrib feature [start | submit | delete]

context-specific usage information for hotfixes:
usage: contrib hotfix [start | submit | delete]

testing:
contrb - returns full usage information
contrib fdfsdfds - returns full usage information
contrib feature - returns context-specific usage information for features
contrib hotfix - returns context-specific usage information for hotfixes
contrib feature FDFWFE - returns context-specific usage information for features
contrib hotfix FDFEWFEE - returns context-specific usage information for hotfixes
contrib feature start/submit/delete - starts the workflow for the specified command
contrib hotfix start/submit/delete - starts the workflow for the specified command
Merge pull request #11 from BCjwhisenant/feature/contrib-usage

added usage information to contrib