Add Welcome to main tab

[pdelboca]

Add title, description and "this year goal" value box to the main page.

• title: "Shiny-Golf: Personal Golf Statistics"
• description: "A few months ago I started playing golf and to write down my results on the cards, I've made this is a shiny app to keep track of my personal golf statistics and to monitor my evolution in the game. Golf + Data + ShinyApps! The objective of 2018 is to have 4 cards in a row without scoring any 10 in a hole."
• This Year Goal: Yes/No if last 4 cards contains any 10.