Enable pin current limiting resistor?
They are saying that you just need a pull-up resistor, so that a logic high is present on the Enable pin. A weak pull-up is all that is needed, with consideration for current draw. Which resistor you use is not a design critical choice, it's left to the designer to figure out (i.e. if you use a bunch of the same value resistor for other pull-ups, use the same here, or if it's battery powered vs ac powered, a higher one is recommended vs a lower one.)

What you need for a weak pull-up:
1) High enough value to limit current draw as needed
2) Low enough to provide the response time needed (Especially in i2c specifications) (i.e. not to interfere with mcu disabling of the regulator)

Too low, and you risk high current draw if you assert the Enable pin (Via button or microcontroller). You also risk your microcontoller not being able to bring the pin down to the correct logic low voltage. 

Too high, and the line won't go from logic low to logic high fast enough, but that's really an issue with communication busses and high frequency timing.

Now, for practical use, if you don't need to disable the regulator, you probably don't need the pull-up resistor. Since this is a user asserted pin, if you assert the pin low, without a pull-up resistor, you would be creating a short circuit (Vcc to ground), but if you have no intention of disabling the regulator, there is no risk of that. Good practice does dictate you add in the resistor though, even if you won't assert the pin.

From Sparkfun's Pull-Up Resistor guide:


  The general rule for condition 2 is to use a pull-up resistor (R1) that is an order of magnitude (1/10th) less than the input impedance (R2) of the input pin. An input pin on a microcontroller has an impedance that varies around 100k-1MOhm. For this discussion, impedance is just a fancy way of saying resistance and is represented by R2 in the picture above. So, when the button is not pressed, a very small amount of current flows from VCC through R1 and into the input pin. The pull-up resistor R1 and input pin impedance R2 divides the voltage, and this voltage needs to be high enough for the input pin to read a high state.