Minor: updated changelog.
-0.?
+0.22.0
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New: ObservationFromRay now returns distance.
+New: Added socket logging code to Mod, available in Mod UI.
+New: Added logging code to platform, available through Malmo API.
+New: startMission now provides more error details in exceptions; multi-agent samples hardened by using this.
+New: ObservationFromNearbyEntities now returns entity life.
0.21.0
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