docs(Readme): update Readme.md (#6229)
docs(Readme): update Readme.md (#6229)

The scrollbar in the code block was bothering me so I cleaned up the build instructions.
dbckr/ui-grid,angular-ui/ng-grid,angular-ui/ng-grid,Servoy/ng-grid,AgDude/ng-grid,InteractiveIntelligence/ng-grid,angular-ui/ui-grid,dbckr/ui-grid,angular-ui/ng-grid,ntmuigrid/ntmuigrid,Servoy/ng-grid,AgDude/ng-grid,Servoy/ng-grid,ntmuigrid/ntmuigrid,angular-ui/ui-grid,dbckr/ui-grid,AgDude/ng-grid,angular-ui/ui-grid,ntmuigrid/ntmuigrid,InteractiveIntelligence/ng-grid,InteractiveIntelligence/ng-grid