Better user messages for __rvm_ask_to_trust().

Improves the user experience by explaining the (un)trust process in more
detail.

scripts/functions/rvmrc

@@ -149,16 +149,27 @@ __rvm_ask_to_trust()
   ===============================================================
   = NOTICE:                                                     =
   ===============================================================
-  = RVM has encountered a not yet trusted .rvmrc file in the    =
-  = current working directory which may contain nasty code.     =
+  = RVM has encountered a new or modified .rvmrc file in the    =
+  = current working directory. Resource files may execute       =
+  = arbitrary instructions, so RVM will not use an .rvmrc file  =
+  = that has not been explicitly marked as 'trusted.'           =
   =                                                             =
-  = Examine the contents of this file to be sure the contents   =
-  = are good before trusting it!                                =
+  = Examine the contents of this file carefully to be sure the  =
+  = contents are good before trusting it!                       =
+  =                                                             =
+  = You will now be given a chance to read the .rvmrc file      =
+  = before deciding whether or not its contents are safe. After =
+  = reading the file, you will be prompted 'yes or no' to set   =
+  = the trust level for this particular version of the file.    =
+  =                                                             =
+  = Note: You will be re-prompted each time the .rvmrc file     =
+  = changes, and may change the trust setting manually at any   =
+  = time.                                                       =
   =                                                             =
   = Press 'q' to exit the reader when finished reading the file =
   ===============================================================
 
-  (press enter to continue when ready)
+  (press enter to review the .rvmrc file)
 
 "
 
@@ -171,11 +182,16 @@ read anykey
   Examining "$1" complete.
 
   ================================================================
-  = Trusting an .rvmrc file means that whenever you cd into the  =
-  = directory RVM will execute this .rvmrc script in your shell  =
+  = Trusting an .rvmrc file means that whenever you cd into this =
+  = directory, RVM will run this .rvmrc script in your shell.    =
+  =                                                              =
+  = If the contents of the file change, you will be re-prompted  =
+  = to review the file and adjust its trust settings. You may    =
+  = also change the trust settings manually at any time with     =
+  = the 'rvm rvmrc' command.                                     =
   =                                                              =
   = Now that you have examined the contents of the file, do you  =
-  = wish to trust this .rvmrc from now on?                       =
+  = wish to trust this particular .rvmrc?                        =
   ================================================================
 
   (yes or no)"