libosmocoding: fix .deb building

dpkg-buildpackage fails due to missing file descriptions - add necessary
.install and .doc-base files to fix it.

Change-Id: I5fb7e813c0860a3b5037e805deb84f9bf649ffa3
diff --git a/debian/libosmocoding-doc.doc-base b/debian/libosmocoding-doc.doc-base
new file mode 100644
index 0000000..a2f3a3a
--- /dev/null
+++ b/debian/libosmocoding-doc.doc-base
@@ -0,0 +1,7 @@
+Document: libosmocoding-doc
+Title: Documentation for the libosmocoding library
+Section: Programming
+
+Format: HTML
+Index: /usr/share/doc/libosmocore/coding/html/index.html
+Files: /usr/share/doc/libosmocore/coding/html/*.html