Editorial: fix "liase" typo in Working Mode

Suggested by Timothy Gu: #177 (review).

Working Mode.md

@@ -145,7 +145,7 @@ Implementation disagreement should not result in implementation-defined behavior
 
 ## Meetings
 
-The WHATWG doesn't generally run any regular meetings. However, as circumstances arise, meetings can be helpful to resolve difficult issues, or to liase with other groups.
+The WHATWG doesn't generally run any regular meetings. However, as circumstances arise, meetings can be helpful to resolve difficult issues, or to liaise with other groups.
 
 Announcements or requests for meetings are to be filed as issues against the relevant Living Standard repository. To allow maximum participation in a meeting, meetings should be announced early and provide an option for remote participation if possible. Transcripts, minutes, or recordings of a meeting should be made available shortly after the meeting concludes (linking from the original meeting request issue is a good way to do this).