docs: fix the type information in in-app-purchase
docs: fix the type information in in-app-purchase

Method returns Boolean, Manually confirmed the
correctness by running `npm run create-api-json`.

electron/electron,shiftkey/electron,seanchas116/electron,bpasero/electron,gerhardberger/electron,seanchas116/electron,shiftkey/electron,gerhardberger/electron,gerhardberger/electron,shiftkey/electron,bpasero/electron,electron/electron,electron/electron,electron/electron,bpasero/electron,the-ress/electron,the-ress/electron,shiftkey/electron,gerhardberger/electron,electron/electron,electron/electron,seanchas116/electron,the-ress/electron,bpasero/electron,the-ress/electron,electron/electron,seanchas116/electron,seanchas116/electron,the-ress/electron,bpasero/electron,gerhardberger/electron,seanchas116/electron,shiftkey/electron,gerhardberger/electron,shiftkey/electron,bpasero/electron,the-ress/electron,bpasero/electron,gerhardberger/electron,the-ress/electron