Add devito to featured projects

[mloubout]

Thanks for letting us in, we've been really happy to rely on sympy since the project infancy (and a few minor PRs to sympy as well)

Cheers

for reference: https://groups.google.com/g/sympy/c/LpTbYAtx6OE

[oscarbenjamin]

I'm not sure if merging this immediately updates the website...

[mloubout]

Looks like it did, thank you.

[certik]

@mloubout thanks, I am glad sympy works for you!