Readme file specifies wrong directory to run Sources/build-linux64.sh

[MartinHowe426]

Issue: The script build-linux64.sh must actually be run from Sources, contrary to the readme file.

/home/martin/Games/Engines/SeriousEngine/Serious-Engine$ Sources/build-linux64.sh
Will build with 'make -j10' ... please edit this script if incorrect.
+ rm -rf cmake-build
+ mkdir cmake-build
+ cd cmake-build
+ cmake -DCMAKE_BUILD_TYPE=Debug ..
CMake Error: The source directory "/home/martin/Games/Engines/SeriousEngine/Serious-Engine" does not appear to contain CMakeLists.txt.
Specify --help for usage, or press the help button on the CMake GUI.

This is because the script assumes that is it being called with Source as CWD, but the readme says to call it from within Serious-Engine:

Sources/build-linux64.sh            # use build-linux32.sh for 32-bits

Changing CWD to Sources and calling build-linux64.sh from there makes cmake work correctly.

Also, looking at the scripts, they all appear to have the same issue.