add source data links to hms lincs db in dataset help box content

[jmuhlich]

• RTK profiling: http://lincs.hms.harvard.edu/db/datasets/20137
• pAKT-pERK: http://lincs.hms.harvard.edu/db/datasets/20140
• dose-response: http://lincs.hms.harvard.edu/db/datasets/20252

[jmuhlich]

Addressed in #282.