fix bsc_vty out: timeslot indented too deeply.

In 'show running-config', timeslot appears as a sub-element of rsl, but it is a
direct child of trx. Fix the timeslot section in vty_out by removing one space
of idention.

Adjust various config examples.

Rationale: it's not relevant for function, but confuses human operators. Fixing
it will save the next hacker some time.
diff --git a/openbsc/doc/examples/osmo-nitb/nanobts/openbsc-multitrx.cfg b/openbsc/doc/examples/osmo-nitb/nanobts/openbsc-multitrx.cfg
index bea0b7d..3277bea 100644
--- a/openbsc/doc/examples/osmo-nitb/nanobts/openbsc-multitrx.cfg
+++ b/openbsc/doc/examples/osmo-nitb/nanobts/openbsc-multitrx.cfg
@@ -59,41 +59,41 @@
    nominal power 23
    max_power_red 0
    rsl e1 tei 0
-    timeslot 0
-     phys_chan_config CCCH+SDCCH4
-    timeslot 1
-     phys_chan_config SDCCH8
-    timeslot 2
-     phys_chan_config TCH/F
-    timeslot 3
-     phys_chan_config TCH/F
-    timeslot 4
-     phys_chan_config TCH/F
-    timeslot 5
-     phys_chan_config TCH/F
-    timeslot 6
-     phys_chan_config TCH/F
-    timeslot 7
-     phys_chan_config TCH/F
+   timeslot 0
+    phys_chan_config CCCH+SDCCH4
+   timeslot 1
+    phys_chan_config SDCCH8
+   timeslot 2
+    phys_chan_config TCH/F
+   timeslot 3
+    phys_chan_config TCH/F
+   timeslot 4
+    phys_chan_config TCH/F
+   timeslot 5
+    phys_chan_config TCH/F
+   timeslot 6
+    phys_chan_config TCH/F
+   timeslot 7
+    phys_chan_config TCH/F
   trx 1
    rf_locked 0
    arfcn 873
    nominal power 23
    max_power_red 0
    rsl e1 tei 0
-    timeslot 0
-     phys_chan_config SDCCH8
-    timeslot 1
-     phys_chan_config TCH/F
-    timeslot 2
-     phys_chan_config TCH/F
-    timeslot 3
-     phys_chan_config TCH/F
-    timeslot 4
-     phys_chan_config TCH/F
-    timeslot 5
-     phys_chan_config TCH/F
-    timeslot 6
-     phys_chan_config TCH/F
-    timeslot 7
-     phys_chan_config TCH/F
+   timeslot 0
+    phys_chan_config SDCCH8
+   timeslot 1
+    phys_chan_config TCH/F
+   timeslot 2
+    phys_chan_config TCH/F
+   timeslot 3
+    phys_chan_config TCH/F
+   timeslot 4
+    phys_chan_config TCH/F
+   timeslot 5
+    phys_chan_config TCH/F
+   timeslot 6
+    phys_chan_config TCH/F
+   timeslot 7
+    phys_chan_config TCH/F