clarification and doc updates

README.md

@@ -12,7 +12,7 @@ User `Tino` is a [basic chatbot](./chatbot) which responds with a [random quote]
 
 [Android demo](https://github.com/tinode/android-example) is mostly stable and functional. See screenshots below. 
 
-The demo server is configured to use [ACME](https://letsencrypt.org/) TLS [implementation](https://godoc.org/golang.org/x/crypto/acme) which has a hard-coded requirement for [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication). If you are unable to connect then the most likely reason is your TLS client missing support for SNI. Use a different client. 
+The demo server is configured to use [ACME](https://letsencrypt.org/) TLS [implementation](https://godoc.org/golang.org/x/crypto/acme) which has a hard-coded requirement for [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication). If you are unable to connect then the most likely reason is your TLS client's missing support for SNI. Use a different client. 
 
 
 ## Why?

server/db/rethinkdb/schema.md

@@ -261,7 +261,7 @@ Sample:
   "SeqIdRanges": [
     {
       "Low": 20,
-	  "Hi": 25,
+      "Hi": 25,
     }
   ] ,
   "Topic":  "grpGx7fpjQwVC0" ,

server/topic.go

@@ -434,11 +434,13 @@ func (t *Topic) run(hub *Hub) {
 					}
 
 					if sess.queueOut(msg) {
-						// Update device map with the device ID which should recive the notification
+						// Update device map with the device ID which should NOT receive the notification.
 						if pushRcpt != nil {
 							if i, ok := pushRcpt.uidMap[sess.uid]; ok {
 								pushRcpt.rcpt.To[i].Delivered++
 								if sess.deviceId != "" {
+									// List of device IDs which already received the message. Push should
+									// skip them.
 									pushRcpt.rcpt.To[i].Devices = append(pushRcpt.rcpt.To[i].Devices, sess.deviceId)
 								}
 							}