Add testimonials

[Keno]

As suggested by @giordano

[giordano]

Start collecting here some comments we've received on Yggdrasil:

• https://github.com/JuliaPackaging/Yggdrasil/pull/366#issuecomment-571969570
• https://github.com/JuliaPackaging/Yggdrasil/pull/539#issuecomment-591668129
• https://twitter.com/ariadneconill/status/1393615304895434754
• https://twitter.com/wuoulf/status/1394721325130915848
• https://github.com/Blosc/c-blosc2/commit/fe135bab842f1f20504f552fccc6e54691dc6e63
• https://twitter.com/Blosc2/status/1395425736597585920

[kagalenko-m-b]

Based on my experience of creating a binary package with BinaryBuilder, I must say, the efficiency of the whole process is almost scary. Julia will eat up Matlab and Python for breakfast, I think