[Fix #543] Do not set tmux destroy-unattached

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>

modules/tmux/README.md

@@ -20,12 +20,15 @@ following line to *zpreztorc*:
 
     zstyle ':prezto:module:tmux:auto-start' remote 'yes'
 
-In both cases, it will create a background session named _#Prezto_ and attach
-every new shell to it.
+In both cases, it will create a background session named _prezto_ if the tmux
+server is not started.
 
-To avoid keeping open sessions, this module sets `destroy-unattached off` on
-the background session and `destroy-unattached on` on every other session
-(global setting).
+With `auto-start` enabled, you may want to control how multiple sessions are
+managed. The `destroy-unattached` option of tmux controls if the unattached
+sessions must be kept alive, making sessions available for later use, configured
+in *tmux.conf*:
+
+    set-option -g destroy-unattached [on | off]
 
 Aliases
 -------
@@ -41,7 +44,7 @@ connected** to be displayed, which can be fixed by installing
 [reattach-to-user-namespace][3], available in [Homebrew][4], and adding the
 following to *tmux.conf*:
 
-   set-option -g default-command "reattach-to-user-namespace -l $SHELL -l"
+    set-option -g default-command "reattach-to-user-namespace -l $SHELL -l"
 
 Furthermore, tmux is known to cause **kernel panics** on Mac OS X. A discussion
 about this and Prezto has already been [opened][2].
@@ -54,6 +57,7 @@ Authors
   - [Sorin Ionescu](https://github.com/sorin-ionescu)
   - [Colin Hebert](https://github.com/ColinHebert)
   - [Georges Discry](https://github.com/gdiscry)
+  - [Xavier Cambar](https://github.com/xcambar)
 
 [1]: http://tmux.sourceforge.net
 [2]: https://github.com/sorin-ionescu/prezto/issues/62