mention starpu_regression_display

doc/starpu.texi

@@ -1278,7 +1278,7 @@ execution times. STARPU_REGRESSION_BASED uses an a*n^b regression
 form, STARPU_NL_REGRESSION_BASED uses an a*n^b+c (more precise than
 STARPU_REGRESSION_BASED, but costs a lot more to compute). For instance,
 @code{tests/perfmodels/regression_based.c} uses a regression-based performance
-model for the @code{memset} operation
+model for the @code{memset} operation.
 
 @item
 Provided explicitly by the application (STARPU_PER_ARCH model type): the
@@ -2097,6 +2097,10 @@ execution, the GPUs are about 20 times faster than the CPUs (numbers are in
 us). The standard deviation is extremely low for the GPUs, and less than 10% for
 CPUs.
 
+The @code{starpu_regression_display} tool does the same for regression-based
+performance models. It also writes a @code{.gp} file in the current directory,
+to be run in the @code{gnuplot} tool, which shows the corresponding curve.
+
 @c ---------------------------------------------------------------------
 @c MPI support
 @c ---------------------------------------------------------------------