Launch documentation: fix double dashes

The documentation suggests that double dashes should be used to use
certain flags. Fix that to consistently document single dashes.

Test: tested locally
Change-Id: Ie9ce9cf6485692b76d06ca54a6402fea850d710e
Signed-off-by: Matthias Maennich <maennich@google.com>
diff --git a/host/commands/launch/main.cc b/host/commands/launch/main.cc
index 4348c5f..0d58afd 100644
--- a/host/commands/launch/main.cc
+++ b/host/commands/launch/main.cc
@@ -75,7 +75,7 @@
 DEFINE_string(blank_data_image_fmt, "ext4",
               "The fs format for the blank data image. Used with mkfs.");
 DEFINE_string(qemu_gdb, "",
-              "Debug flag to pass to qemu. e.g. --qemu_gdb=tcp::1234");
+              "Debug flag to pass to qemu. e.g. -qemu_gdb=tcp::1234");
 
 DEFINE_int32(x_res, 720, "Width of the screen in pixels");
 DEFINE_int32(y_res, 1280, "Height of the screen in pixels");
@@ -155,11 +155,11 @@
               "as in 'usb,tunnel'");
 DEFINE_bool(run_adb_connector, true,
             "Maintain adb connection by sending 'adb connect' commands to the "
-            "server. Only relevant with --adb_mode=tunnel");
+            "server. Only relevant with -adb_mode=tunnel");
 DEFINE_string(adb_connector_binary,
               vsoc::DefaultHostArtifactsPath("bin/adb_connector"),
               "Location of the adb_connector binary. Only relevant if "
-              "--run_adb_connector is true");
+              "-run_adb_connector is true");
 DEFINE_int32(vhci_port, GetPerInstanceDefault(0), "VHCI port to use for usb");
 DEFINE_string(guest_mac_address,
               GetPerInstanceDefault("00:43:56:44:80:"), // 00:43:56:44:80:0x