Add ref:isil=* for libraries

data/presets/fields/ref/isil.json

@@ -0,0 +1,5 @@
+{
+    "key": "ref:isil",
+    "type": "text",
+    "label": "International Standard Identifier for Libraries and Related Organisations"
+}

data/presets/presets/amenity/library.json

@@ -8,7 +8,8 @@
         "opening_hours",
         "internet_access",
         "internet_access/fee",
-        "internet_access/ssid"
+        "internet_access/ssid",
+        "ref/isil"
     ],
     "geometry": [
         "point",