Improve resin update help section

build/actions/update.js

@@ -12,7 +12,7 @@
   exports.update = {
     signature: 'update',
     description: 'update the resin cli',
-    help: 'Use this command to update the Resin CLI\n\nThis command outputs information about the update process.\nUse `--quiet` to remove that output.\n\nExamples:\n\n	$ resin update',
+    help: 'Use this command to update the Resin CLI\n\nThis command outputs information about the update process.\nUse `--quiet` to remove that output.\n\nThe Resin CLI checks for updates once per day.\n\nMajor updates require a manual update with this update command,\nwhile minor updates are applied automatically.\n\nExamples:\n\n	$ resin update',
     action: function(params, options, done) {
       return async.waterfall([
         function(callback) {

doc/update/update.md

@@ -5,6 +5,11 @@ Use this command to update the Resin CLI
 This command outputs information about the update process.
 Use `--quiet` to remove that output.
 
+The Resin CLI checks for updates once per day.
+
+Major updates require a manual update with this update command,
+while minor updates are applied automatically.
+
 Examples:
 
 	$ resin update

lib/actions/update.coffee

@@ -12,6 +12,11 @@ exports.update =
 		This command outputs information about the update process.
 		Use `--quiet` to remove that output.
 
+		The Resin CLI checks for updates once per day.
+
+		Major updates require a manual update with this update command,
+		while minor updates are applied automatically.
+
 		Examples:
 
 			$ resin update