feat: openfoam logo seems too big

[wesleyboar]

Warning

Instead, update logo; search.

Reduced size of OpenFOAM logo.

The logo seems unnecessarily large.

Why?

Because:

• the image resolution is too poor to merit that size
  ^{At a large size, the poor resolution is highlighted.}
• the logo is clear, even at smaller size
  ^{It's a blue triangle outline with weighted lines.}

before	after