[doc] update readme to linux warnings and standalone

README.md

@@ -33,6 +33,21 @@ Using homebrew:
 
 ```
 
+Linux
+----------
+Building the systray in linux will produce some `-Wdeprecated-declarations` warnings, like that:
+```
+cgo-gcc-prolog: In function ‘_cgo_3f9f61f961c9_Cfunc_gtk_font_button_get_font_name’:
+cgo-gcc-prolog:5455:2: warning: ‘gtk_font_button_get_font_name’ is deprecated [-Wdeprecated-declarations]
+In file included from /usr/include/gtk-3.0/gtk/gtk.h:106:0,
+                 from ../../../go/src/github.com/gotk3/gotk3/gtk/gtk.go:48:
+/usr/include/gtk-3.0/gtk/gtkfontbutton.h:96:23: note: declared here
+ const gchar *         gtk_font_button_get_font_name  (GtkFontButton *font_button);
+                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+```
+They are expected and don't produce any problem on the systray.
+
+
 Run it
 -------------
 bitmask-systray assumes that you already have bitmaskd running.
@@ -43,6 +58,18 @@ Run bitmask and the systray:
   $ ./bitmask-systray
 ```
 
+Standalone
+-------------
+
+Is also posible to compile the systray to be standalone (don't depend on bitmask):
+```
+  $ go build -tags standalone
+```
+It still requires a helper and openvpn installed to work. For linux the helper is
+[bitmask-root](https://0xacab.org/leap/bitmask-dev/blob/master/src/leap/bitmask/vpn/helpers/linux/bitmask-root)
+for windows and OSX there is [a helper written in go](https://0xacab.org/leap/riseup_vpn/tree/master/helper).
+
+
 i18n
 ----