fix typo in redirect

Author: kay-kim

config/redirects

@@ -1386,7 +1386,7 @@ raw: /master/release-notes/3.0-general-improvements -> ${base}/release-notes/3.0
 [v4.0-*]: /${version}/reference/program/mongoperf -> ${base}/${version}/reference/program
 
 # Redirects for 3.6 or earlier 
-[*-v3.6] /${version}/reference/read-concern-snapshot -> ${base}/${version}/reference/read-concern
+[*-v3.6]: /${version}/reference/read-concern-snapshot -> ${base}/${version}/reference/read-concern
 
 # 2.8 compatibility
 [*]: /${version}/release-notes/2.8-downgrade -> ${base}/${version}/release-notes