📝 Better description of Pick mapped type
📝 Better description of Pick mapped type

closes https://github.com/Microsoft/TypeScript/issues/25976
Microsoft/TypeScript,weswigham/TypeScript,donaldpipowitch/TypeScript,minestarks/TypeScript,minestarks/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,alexeagle/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,basarat/TypeScript,weswigham/TypeScript,minestarks/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,microsoft/TypeScript,kitsonk/TypeScript,nojvek/TypeScript,microsoft/TypeScript,SaschaNaz/TypeScript,Microsoft/TypeScript,RyanCavanaugh/TypeScript,RyanCavanaugh/TypeScript,microsoft/TypeScript,nojvek/TypeScript,SaschaNaz/TypeScript,kitsonk/TypeScript,alexeagle/TypeScript,donaldpipowitch/TypeScript,RyanCavanaugh/TypeScript,kitsonk/TypeScript,basarat/TypeScript,Microsoft/TypeScript,donaldpipowitch/TypeScript,donaldpipowitch/TypeScript,SaschaNaz/TypeScript,basarat/TypeScript,alexeagle/TypeScript,weswigham/TypeScript,basarat/TypeScript