Update css-anchor-position-1/Overview.bs

Co-authored-by: Connor Pearson <cjpearson@users.noreply.github.com>

Author: 2 people

css-anchor-position-1/Overview.bs

@@ -345,7 +345,7 @@ with each other and their containing blocks.
 The list of conditions below
 exactly rephrases the stacking context rules
 into just what's relevant for this purpose,
-ensuring there is no possibilitly of circularity
+ensuring there is no possibility of circularity
 in anchor positioning.
 
 <div algorithm>