Comment on `Wire.read()` reference: "slave may send less than requested" is misleading

In the documentation of [Wire.read()](https://www.arduino.cc/en/Reference/WireRead) is this example:
```
#include

void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
Serial.begin(9600); // start serial for output
}

void loop()
{
Wire.requestFrom(2, 6); // request 6 bytes from slave device arduino/Arduino#2

while(Wire.available()) // slave may send less than requested
{
char c = Wire.read(); // receive a byte as character
Serial.print(c); // print the character
}

delay(500);
}
```
The comment "slave may send less than requested" is misleading.
Some might think that they have to wait for the rest of the bytes to arrive. Some might think that the Slave can decide to send less bytes, even when there was no bus error.

It is however inherit to the I2C protocol that the Slave can not send less or more than requested. If the Slave stops sending data, then the SDA will stay high and the Master will read 0xFF. The Master will continue to read all the bytes and does not know that the 0xFF is not valid data from the Slave. When reading data from a Slave, the Master provides the SCL clock signal, the ACK between the data bytes and the STOP at the end. The Slave has no way to influence that.

Start from the linked Wire.read() reference page and inspect the example containing the “slave may send less than requested” comment. Check the wording against the documented behavior of Wire.requestFrom() and Wire.read(); done means the example no longer suggests that a slave can arbitrarily send fewer bytes or that a reader should wait for more data.

Written by the indexing model from the issue text.