Replace "position" with "seat" in two places

"Position" is elsewhere used in a different context, and "seat" is
elsewhere always used in this context (i.e. to mean one of the 7 "slots"
of the SC that may or may not be filled).

This makes the terminology more consistent.

Author: Ericson2314

doc/constitution.md

@@ -197,8 +197,8 @@ If it is impossible to find sufficient members to resign, all members with that
 
 #### Special Elections
 
-In the event of a resignation or other loss of a steering committee member (including a [removal for conduct](#removal-for-conduct)), a special election for that position may be held if the SC deems it necessary, or the SC does not have half of the normal size.
-Otherwise, the missing positions are assumed to be abstaining from all the SC votes.
+In the event of a resignation or other loss of a steering committee member (including a [removal for conduct](#removal-for-conduct)), a special election for that seat may be held if the SC deems it necessary, or the SC does not have half of the normal size.
+Otherwise, the missing seats are assumed to be abstaining from all the SC votes.
 A committee member elected in a special election will serve out the remainder of the term of the person they are replacing, regardless of the length of that remainder.
 
 #### Full Reelections