Add full stop to ChangeLog entry

ChangeLog

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    * Add alternative implementation support for CCM and CMAC (MBEDTLS_CCM_ALT,
      MBEDTLS_CMAC_ALT). Submitted by Steve Cooreman, Silicon Labs.
    * Add support for alternative implementations of GCM, selected by the
-     configuration flag MBEDTLS_GCM_ALT in config.h
+     configuration flag MBEDTLS_GCM_ALT.
 
 New deprecations
    * Deprecate usage of RSA primitives with non-matching key-type