Add TODO-RELEASE file

Let's track the API/ABI changes in libosmo*mgcp the same way we do it in
other libosmo* libraries.

Change-Id: Id0b8d55ea58bdb3d72b4c131ac983d8895b55ef8
diff --git a/TODO-RELEASE b/TODO-RELEASE
new file mode 100644
index 0000000..d0852fc
--- /dev/null
+++ b/TODO-RELEASE
@@ -0,0 +1,9 @@
+# When cleaning up this file: bump API version in corresponding Makefile.am and rename corresponding debian/lib*.install
+# according to https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html#Updating-version-info
+# In short:
+# LIBVERSION=c:r:a
+# If the library source code has changed at all since the last update, then increment revision: c:r + 1:a.
+# If any interfaces have been added, removed, or changed since the last update: c + 1:0:0.
+# If any interfaces have been added since the last public release: c:r:a + 1.
+# If any interfaces have been removed or changed since the last public release: c:r:0.
+#library	what		description / commit summary line