source/base: Fix docs for owning constructor

Change-Id: I22667a652bc4db8afc05aea1736b678a213a7e89
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/sdeventplus/source/base.hpp b/src/sdeventplus/source/base.hpp
index eeef626..e86b405 100644
--- a/src/sdeventplus/source/base.hpp
+++ b/src/sdeventplus/source/base.hpp
@@ -121,6 +121,7 @@
      *
      *  @param[in] event  - The event associated with the source
      *  @param[in] source - The underlying sd_event_source wrapped
+     *  @param[in]        - Signifies that ownership is being transfered
      *  @throws SdEventError for underlying sd_event errors
      */
     Base(const Event& event, sd_event_source* source, std::false_type);