minor: Fix typo in summary.
minor: Fix typo in summary.

The summary for add_code_playground wrongly mentions
'Remove' instead of 'Add' in the summary. Fixed the typo.

hackerkid/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,zulip/zulip,eeshangarg/zulip,zulip/zulip,zulip/zulip,kou/zulip,andersk/zulip,rht/zulip,andersk/zulip,rht/zulip,kou/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,eeshangarg/zulip,zulip/zulip,punchagan/zulip,eeshangarg/zulip,punchagan/zulip,punchagan/zulip,kou/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,andersk/zulip,andersk/zulip,zulip/zulip,rht/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,punchagan/zulip,rht/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,kou/zulip,hackerkid/zulip,eeshangarg/zulip