Build Instructions: Add separate doc folder for building instructions.  Add Linux/Make guide.
Build Instructongs: For Linux/Make, fix .git/info/exclude section and add link to readme.
Update readme.md
Readme: Add link to building instructions documentation.
Build Instructions: Add visual studio.
BuildingReadme: Add VS hyperlink.
Build Instructions: Updated visual studio instructions for cmake.
Fix `Compiling` header.
Fix compile types in VS instructions, handled by VS not CMake
Merge pull request #116 from Astron/build-instructions

More detailed instructions for building Astron