update README

Author: zingale

examples/extensions/pybind11/README

@@ -1,7 +1,7 @@
 
 pip install pybind11
 
-g++ -O3  -Wall -Wextra -shared -std=c++17 -fPIC $(python3 -m pybind11 --includes) mandel.cpp -o mandel$(python3-config --extension-suffix)
+g++ -O3 -DNDEBUG -Wall -Wextra -shared -std=c++17 -fPIC $(python3 -m pybind11 --includes) mandel.cpp -o mandel$(python3-config --extension-suffix)
 
 
 see https://stackoverflow.com/questions/44659924/returning-numpy-arrays-via-pybind11

examples/extensions/pybind11/contiguous/README

@@ -2,7 +2,7 @@ This version uses a simple Array class to give us nice indexing into a contiguou
 
 pip install pybind11
 
-g++ -DNDEBUG -O3  -Wall -Wextra -shared -std=c++17 -fPIC $(python3 -m pybind11 --includes) mandel.cpp -o mandel$(python3-config --extension-suffix)
+g++ -DNDEBUG -O3 -Wall -Wextra -shared -std=c++17 -fPIC $(python3 -m pybind11 --includes) mandel.cpp -o mandel$(python3-config --extension-suffix)
 
 
 see https://stackoverflow.com/questions/44659924/returning-numpy-arrays-via-pybind11