Update readme compatibility for RN < 60

[1Jesper1]

As seen in https://github.com/software-mansion/react-native-gesture-handler/releases/tag/1.4.0
It is possible to use this release with RN < 0.60 but one have to rely on reverse-jetifying of gesture handler library. Read more on that here https://github.com/mikehardy/jetifier#to-reverse-jetify--convert-node_modules-dependencies-to-support-libraries

Please include this in the Readme.
Till 1.10.3 it seems to work with RN 0.59.10.

[jgonet]

#1548

[1Jesper1]

Nice!