doxygen: Fix all the "\returns" so they work as part of complete sentences.

include/SDL_test_harness.h

@@ -105,7 +105,7 @@ typedef struct SDLTest_TestSuiteReference {
  *
  * \param length The length of the seed string to generate
  *
- * \returns The generated seed string
+ * \returns the generated seed string
  */
 char *SDLTest_GenerateRunSeed(const int length);
 
@@ -118,7 +118,7 @@ char *SDLTest_GenerateRunSeed(const int length);
  * \param filter Filter specification. NULL disables. Case sensitive.
  * \param testIterations Number of iterations to run each test case.
  *
- * \returns Test run result; 0 when all tests passed, 1 if any tests failed.
+ * \returns the test run result: 0 when all tests passed, 1 if any tests failed.
  */
 int SDLTest_RunSuites(SDLTest_TestSuiteReference *testSuites[], const char *userRunSeed, Uint64 userExecKey, const char *filter, int testIterations);