Readme example broken

[liyishuai]

The README example needs to be updated per #202, which removed SetWebhook:

telegram-bot-api/README.md

Line 90 in 4fe428c

_, err = bot.SetWebhook(wh)

Originally posted by @liyishuai in #202 (comment)

[Syfaro]

Thanks for opening this issue! I heard this was an issue but it had slipped my mind.

Should be fixed by 60c16b6.