Check{,C,CXX,OBJC,OBJCXX,Fortran}SourceCompiles: Update documentation
Changes:
- Added intro code blocks showing how to include these modules.
- Added examples sections.
- Used "command" instead of "macro".
- Commands sections added to have a clearer overview of the modules at
first encounter.
- Reworded commands arguments a bit.
- Added a rubric title for variables that affect the checks.
- CheckFortranSourceCompiles: Added CMake version when SRC_EXT option
was introduced.
- Listed CMAKE_TRY_COMPILE_TARGET_TYPE variable in the rubric together
with CMAKE_REQUIRED_* variables and added an include RST file for it.
- Used lowercase style for check_fortran_source_compiles().
12 files changed
