Add Changelog entry

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/ChangeLog.d/nonversioned-library-soname.txt b/ChangeLog.d/nonversioned-library-soname.txt
new file mode 100644
index 0000000..8d83a2d
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+++ b/ChangeLog.d/nonversioned-library-soname.txt
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+Features
+   * make: enable building unversioned shared library, with e.g.:
+     "SHARED=1 SOEXT_TLS=so SOEXT_X509=so SOEXT_CRYPTO=so make lib"
+     resulting in library names like "libmbedtls.so" rather than
+     "libmbedcrypto.so.11".