Update on microcontrollers/arduino-mega2560, I2C support corrected

[habdig7oficial]

Hello after, a discussion in the tinygo slack, one of the maintainers said that the I2C support on arduino-mega2560 was wrong indicating that it have support when it doesn't so I corrected the documentation page

I look forward to I2C support on tinygo, but until there the documentation page needs to be corrected, later i will see if I can use it with arduino-uno whose page also says to have I2C.

Thank you all for the support! :)

[aykevl]

Unfortunately this part of the documentation is autogenerated, so it will be overwritten on the next update.
It's still a bug, but ideally it should be fixed at the source: https://github.com/tinygo-org/tinygo-site/blob/release/doc-gen/main.go
(The issue is that it just checks whether the I2C type exists, it doesn't check whether there are actually any peripherals of the type I2C).