monitor: Schema proofreading

Typos and fix of description, was wrongly copy&pasted from master.

software/monitor/instance-edgetest-input-schema.json

@@ -22,7 +22,7 @@
     "check-certificate-expiration-days": {
       "default": "15",
       "title": "Default certificate expiration days check",
-      "description": "Default amount of days to consider certitifcate as being to-be-expired (default: 15).",
+      "description": "Default amount of days to consider certificate as being to-be-expired (default: 15).",
       "type": "string"
     }
   }

software/monitor/instance-edgetest-slave-input-schema.json

@@ -21,7 +21,7 @@
     "check-certificate-expiration-days": {
       "default": "Master default",
       "title": "Certificate expiration days check",
-      "description": "Default amount of days to consider certitifcate as being to-be-expired (default: comes from master partition).",
+      "description": "Amount of days to consider certificate as being to-be-expired (default: comes from master partition).",
       "type": "string"
     }
   }