[doc] Fix meson build options in README

Signed-off-by: Jianhui Dai <jianhui.j.dai@intel.com>
diff --git a/README.md b/README.md
index e583505..8fc97ea 100644
--- a/README.md
+++ b/README.md
@@ -40,7 +40,7 @@
 ```
 mkdir build
 cd build
-meson .. or meson .. -Denable-tests
+meson .. or meson .. -Dtests=true
 ninja
 sudo ninja install
 ```
@@ -74,4 +74,4 @@
       VAProfileVP9Profile0            : VAEntrypointVLD
       VAProfileVP9Profile2            : VAEntrypointVLD
       ...
-```
\ No newline at end of file
+```