I've always found showing someone how to hold a pick pretty hard.
I don't hold it like that picture, but I guess it's all preference on whats easier for you.
But holding it like the picture doesn't seem like a good idea, it looks like the rest of your hand would get in the way and your strumming would be really strange.

I hold it between my thumb and my index finger, and a little bit outwards
wutever is more confortable for you... but try holding it like paul gilbert and see if u like it.. that the way i hold it most of the time and it suites me very well...
if you dont like it then you can try different possitions
It really just comes down to preference, there is no '' correct'' way to hold it, just whatever feels the most comfortable and efficient for you
No Money, No Honey.
Whichever is most comfortable/natural feeling to you. I personally prefer between just thumb & index. Paul Gilbert used to hold his pick with thumb, index and middle until he noticed how it affected his picking speed.
Jackson Kelly KE3 w/P-Rails; Aria Pro II TSB-350
• ZVex Fuzz Factory; DigiTech Whammy; Danelectro Fish & Chips; Marshall ED1; Fulltone OCD; DigiTech Whammy; Marshall JMP1; Boss CE3; Vox AC4TV

EMU 0404; Reason/Record; M-Audio AV40
It is more about what is comfortable for you, what type of pick and style you play. I use a Dunlop Ultex Jazz III pick and the method shown in that link you provided would have the pick sitting way to deep for me. My index is almost straight from the first knuckle down, with just a slight bend at the end knuckle. Experiment with different picks and different ways of holding till you find what works best for you and the styles you play.
Quote by dale-banez

my gear:
oh wait, no one cares

Quote by uncboy19
man all guitars are female. if they werent you couldn't make sweet love to them with your fingers. ok somebody better quote that ****. thats like quantum guitar **** rite there.
Eddie Van Halen Holds it between his thumb and Middle Finger so he can switch to tapping faster.
When the power of love overcomes the love for power, the world will know peace. ~Jimi Hendrix

For me it depends on what I'm playing. If I'm strumming or hybrid picking I'll let the pick out a little bit more. If I'm shredding I'll choke up on the pick. Be sure to get some light, medium, and hard picks to see what works best for you.
I've been told by many guitarists that there should be no "law" on how to hold the pick, hold it as you think it's best and easiest for you, you should try various combinations, play every combination a bit, like 3-4 songs and see how it goes, at least, that's how I found my "pick-holding"