Fix typo in README
Fix typo in README

The word "than" was used when the word "then" was likely intended.
realm/jazzy,PSPDFKit-labs/jazzy,pcantrell/jazzy,PSPDFKit-labs/jazzy,Kapeli/jazzy,agentk/jazzy,1ec5/jazzy,realm/jazzy,pcantrell/jazzy,agentk/jazzy,Kapeli/jazzy,pcantrell/jazzy,agentk/jazzy,Kapeli/jazzy,1ec5/jazzy,1ec5/jazzy