add telemetry option to docs

README.md

@@ -138,6 +138,9 @@ require('greenlock-express').create({
   // Join the community to get notified of important updates and help me make greenlock better
 , communityMember: true
 
+  // Contribute telemetry data to the project
+, telemetry: true
+
 //, debug: true
 
 }).listen(80, 443);
@@ -285,6 +288,9 @@ var glx = require('greenlock-express').create({
   , webrootPath: '/tmp/acme-challenges'
   })
 
+  // Contribute telemetry data to the project
+, telemetry: true
+
 , approveDomains: approveDomains
 });
 ```