CONTRIBUTING.md: Update cask examples (#905)
CONTRIBUTING.md: Update cask examples (#905)

Due that `license` stanza has been removed and string variable interpolation can be used I think that both cask examples should be updated to avoid new users feel confused.
unasuke/homebrew-fonts,alerque/homebrew-fonts,guerrero/homebrew-fonts,guerrero/homebrew-fonts,alerque/homebrew-fonts