README: Add instruction to check MD5 sum of the downloaded source package
README: Add instruction to check MD5 sum of the downloaded source package

thewtex/python-cmake-buildsystem,python-cmake-buildsystem/python-cmake-buildsystem,adrianbroher/python-cmake-buildsystem,chuckatkins/python-cmake-buildsystem,msmolens/python-cmake-buildsystem,jcfr/python-cmake-buildsystem,davidsansome/python-cmake-buildsystem,thewtex/python-cmake-buildsystem