fixed typo

coreplugins/cesiumion/manifest.json

@@ -6,7 +6,7 @@
 	"author": "Cesium GS, Inc",
 	"email": "hello@cesium.com",
 	"repository": "",
-	"tags": ["cesium ion", "ceium"],
+	"tags": ["cesium ion", "cesium"],
 	"homepage": "https://cesium.com",
 	"experimental": false,
 	"deprecated": false