Update constants.adoc

Added missing word and corrected spelling

Author: kengdahl

Language/Variables/Constants/constants.adoc

@@ -44,7 +44,7 @@ The meaning of `HIGH` (in reference to a pin) is somewhat different depending on
   - a voltage greater than 2.0V volts is present at the pin (3.3V boards)
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-A pin may also be configured as an INPUT with link:../../../functions/digital-io/pinmode[`pinMode()`], and subsequently made HIGH with `link:../../../functions/digital-io/digitalwrite[digitalWrite()]`. This will enable the internal 20K pullup resistors, which will _pull up_ the input pin to a `HIGH` reading unless it is pulled `LOW` by external circuitry. This can done alternatively by passing `INPUT_PULLUP` as argument to the link:../../../functions/digital-io/pinmode[`pinMode()`] funtion, as explained in more detail in the section "Defining Digital Pins modes: INPUT, INPUT_PULLUP, and OUTPUT" further below.
+A pin may also be configured as an INPUT with link:../../../functions/digital-io/pinmode[`pinMode()`], and subsequently made HIGH with `link:../../../functions/digital-io/digitalwrite[digitalWrite()]`. This will enable the internal 20K pullup resistors, which will _pull up_ the input pin to a `HIGH` reading unless it is pulled `LOW` by external circuitry. This can be done alternatively by passing `INPUT_PULLUP` as argument to the link:../../../functions/digital-io/pinmode[`pinMode()`] function, as explained in more detail in the section "Defining Digital Pins modes: INPUT, INPUT_PULLUP, and OUTPUT" further below.
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 When a pin is configured to OUTPUT with link:../../../functions/digital-io/pinmode[`pinMode()`], and set to `HIGH` with link:../../../functions/digital-io/digitalwrite[`digitalWrite()`], the pin is at: