Document chromeTransactionDurability
Document chromeTransactionDurability

Also updates to use markdown tables rather than HTML, per the suggestion [here](https://github.com/dfahlander/Dexie.js/pull/1367#issuecomment-891008856)
dfahlander/dexie.js-web,dfahlander/dexie.js-web,dfahlander/dexie.js-web,dfahlander/dexie.js-web