charts: Rename voice_call_full.msc to voice_call_external_mncc.msc

Because I will soon add an _internal_mncc one as well.

Change-Id: Ic90a93d749ea936a632a45e615007a58104eeedd
diff --git a/doc/sequence_charts/Makefile.am b/doc/sequence_charts/Makefile.am
index c119458..f71d934 100644
--- a/doc/sequence_charts/Makefile.am
+++ b/doc/sequence_charts/Makefile.am
@@ -15,7 +15,7 @@
 	$(builddir)/mncc_call_fsm.png \
 	$(builddir)/inter_bsc_ho.png \
 	$(builddir)/inter_msc_ho.png \
-	$(builddir)/voice_call_full.png \
+	$(builddir)/voice_call_external_mncc.png \
 	$(builddir)/call_reestablishment.png \
 	$(NULL)
 
diff --git a/doc/sequence_charts/voice_call_full.msc b/doc/sequence_charts/voice_call_external_mncc.msc
similarity index 100%
rename from doc/sequence_charts/voice_call_full.msc
rename to doc/sequence_charts/voice_call_external_mncc.msc