cosmetic: OsmoGSMTester: fix dir name

All other subdirs are without dashes, but I added Osmo-GSM-Tester with dashes.
Comply with the naming scheme and remove dashes.

Change-Id: I36d0c94dde5deffba04b27436ae499a42c519bec
diff --git a/doc/manuals/Makefile b/doc/manuals/Makefile
new file mode 100644
index 0000000..79d414f
--- /dev/null
+++ b/doc/manuals/Makefile
@@ -0,0 +1,12 @@
+TOPDIR := ..
+ASCIIDOCS := osmo-gsm-tester-manual
+
+include $(TOPDIR)/build/Makefile.asciidoc.inc
+include $(TOPDIR)/build/Makefile.inc
+
+osmo-gsm-tester-manual.pdf: chapters/*.adoc
+
+clean:
+	-rm -rf $(cleanfiles)
+	-rm osmo-gsm-tester-manual__*.svg
+	-rm osmo-gsm-tester-manual__*.png