README.keystrokes: refine description

doc/nxagent/README.keystrokes

@@ -58,12 +58,13 @@ usually you will need Mod1 and Control. Boolean in this context means
 '0', 'false' and an unspecified attribute are false, anything else is
 considered true.
 
-Everything in this file is case-sensitive. Unknown lines are ignored.
-Keybindings are evaluated from top to bottom, so if a keybinding
-matches, other keybindings further down will be ignored. The contents
-of the file replaces the default keybindings, and only one file is
-read, no merging between different configuration files is done. This
-also means that an empty or invalid configuration file deactivates all
+Everything in this file is case-sensitive. Unknown lines are ignored
+(accompanied by a warning in the session log).  Keybindings are
+evaluated from top to bottom, so if a keybinding matches, other
+keybindings further down will be ignored. The contents of the file
+replaces the default keybindings, and only one file is read, no
+merging between different configuration files is done. This also means
+that an empty or invalid configuration file deactivates all
 keybindings.
 
 If an attribute occurs more than once in a line the last one wins.
@@ -72,7 +73,10 @@ List of possible 'action' attributes:
 -------------------------------------
 
 close_session
-  This terminates the session.
+  This terminates the session. If a proper helper is available
+  (NX_CLIENT environment variable point to e.g. nxdialog path) this
+  will ask the user if he want to suspend or terminate the session,
+  otherwise it will terminate without askting.
 
 fullscreen
   Switches the client window into or out of fullscreen mode, using
@@ -102,7 +106,9 @@ defer
 
 ignore
   Ignores the following keystroke, nothing will happen when this
-  keystroke is pressed.
+  keystroke is pressed. The keystroke will NOT be passed to the
+  clients. If you want the clients to see the keystroke you need to
+  eliminate the line from the config file instead of using 'ignore'.
 
 reread_keystrokes
   Forces nxagent to re-read the keystroke configuration. Useful to