Clarify tha snmp node oids must be numeric

docs only

io/snmp/package.json

@@ -1,6 +1,6 @@
 {
     "name"          : "node-red-node-snmp",
-    "version"       : "0.0.19",
+    "version"       : "0.0.20",
     "description"   : "A Node-RED node that looks for SNMP oids.",
     "dependencies"  : {
         "net-snmp"  : "1.2.4"

io/snmp/snmp.html

@@ -32,6 +32,7 @@
     <p><code>msg.host</code> may contain the host.</p>
     <p><code>msg.community</code> may contain the community.</p>
     <p><code>msg.oid</code> may contain a comma separated list of oids to request. (no spaces)</p>
+    <p>OIDs must be numeric. iso. is the same a 1. </p>
     <p>The node will output <code>msg.payload</code> and <code>msg.oid</code>.</p>
 </script>
 
@@ -101,6 +102,7 @@
     },
     {   "oid":   ... }
 ]</pre>
+    <p>OIDs must be numeric. iso. is the same a 1.</p>
     </p>
 </script>
 
@@ -162,6 +164,7 @@
     <p><code>msg.host</code> may contain the host.</p>
     <p><code>msg.community</code> may contain the community.</p>
     <p><code>msg.oid</code> may contain the oid of a table to request.</p>
+    <p>OID must be numeric. iso. is the same a 1.</p>
     <p>The node will output <code>msg.payload</code> and <code>msg.oid</code>.</p>
 </script>
 
@@ -223,6 +226,7 @@
     <p><code>msg.host</code> may contain the host.</p>
     <p><code>msg.community</code> may contain the community.</p>
     <p><code>msg.oid</code> may contain the oid of a table to request.</p>
+    <p>OID must be numeric. iso. is the same a 1. </p>
     <p>The node will output <code>msg.payload</code> and <code>msg.oid</code>.</p>
 </script>
 
@@ -285,6 +289,7 @@
     <p><code>msg.host</code> may contain the host.</p>
     <p><code>msg.community</code> may contain the community.</p>
     <p><code>msg.oid</code> may contain the oid of a table to request.</p>
+    <p>OID must be numeric. iso. is the same a 1. </p>
     <p>The node will output <code>msg.payload</code> and <code>msg.oid</code>.</p>
 </script>