docs: document how setAsDefaultProtocolClient works in Windows Store (#16874)
docs: document how setAsDefaultProtocolClient works in Windows Store (#16874)

Closes #16852
electron/electron,bpasero/electron,seanchas116/electron,electron/electron,the-ress/electron,electron/electron,seanchas116/electron,electron/electron,seanchas116/electron,the-ress/electron,bpasero/electron,gerhardberger/electron,electron/electron,gerhardberger/electron,bpasero/electron,the-ress/electron,bpasero/electron,bpasero/electron,the-ress/electron,bpasero/electron,gerhardberger/electron,gerhardberger/electron,the-ress/electron,seanchas116/electron,the-ress/electron,gerhardberger/electron,bpasero/electron,the-ress/electron,electron/electron,seanchas116/electron,seanchas116/electron,electron/electron,gerhardberger/electron,gerhardberger/electron