Add argument examples in install.sh-usage

Author: Damian Rouson

install.sh-usage

@@ -1,25 +1,25 @@
-  -b --install-branch [arg]   Install the specified repository development branch.
-  -B --list-branches [arg]    List the available branches in the specified package's repository.
-  -c --with-c [arg]           Use specified C compiler.
-  -C --with-cxx [arg]         Use specified C++ compiler.
-  -d --debug                  Enable debug mode.
-  -D --print-downloader [arg] Print download program for package specified in argument.
+  -b --install-branch [arg]   Install the specified repository development branch (Examples: -b trunk or -b gcc-7-branch).
+  -B --list-branches [arg]    List the available branches in the specified package's repository (Example: -B gcc).
+  -c --with-c [arg]           Use specified C compiler (Example: -c /usr/local/bin/gcc).
+  -C --with-cxx [arg]         Use specified C++ compiler (Example: -C /usr/local/bin/g++).
+  -d --debug                  Enable debug mode. 
+  -D --print-downloader [arg] Print download program for package specified in argument (Example: -D gcc).
   -e --verbose                Enable verbose mode, print script as it is executed.
-  -f --with-fortran [arg]     Use specified Fortran compiler.
+  -f --with-fortran [arg]     Use specified Fortran compiler (Example: -f /usr/local/bin/gfortran).
   -h --help                   Print this page.
   -i --install-prefix [arg]   Install package in specified path. Default="${OPENCOARRAYS_SRC_DIR}/prerequisites/installations/${package_name:-}/${version_to_build:-}"
-  -I --install-version [arg]  Install package version.
-  -j --num-threads [arg]      Number of threads to use when invoking make. Default="1"
+  -I --install-version [arg]  Install package version (Example: -I 7.2.0).
+  -j --num-threads [arg]      Number of threads to use when invoking make (Example: -j 4). Default="1"
   -l --list-packages          Print packages this script can install.
-  -m --with-cmake [arg]       Use specified CMake installation.
-  -M --with-mpi [arg]         Use specified MPI installation.
+  -m --with-cmake [arg]       Use specified CMake installation (Example: -m /usr/local/bin/cmake).
+  -M --with-mpi [arg]         Use specified MPI installation (Examples: -M /usr/local/ or -m /opt/mpich-3.2/).
   -n --no-color               Disable color output.
   -o --only-download          Download (without building) the source for the package specified by -p or --package.
-  -p --package [arg]          Install specified package. Default="opencoarrays"
-  -P --print-path [arg]       Print installation directory for specified package.
-  -u --from-url [arg]         Specify a URL to use for downloading a package.
-  -U --print-url [arg]        Print download location for specified package.
+  -p --package [arg]          Install specified package (Examples: -p gcc or -p mpich). Default="opencoarrays"
+  -P --print-path [arg]       Print installation directory for specified package (Example: -P gcc).
+  -u --from-url [arg]         Specify a URL to use for downloading a package (Example: -u https://github.com/sourceryinstitute/gcc/archive/teams-rc3.tar.gz).
+  -U --print-url [arg]        Print download location for specified package (Example: -U gcc).
   -v --version                Print OpenCoarrays version number.
-  -V --print-version [arg]    Print version number for specified package.
+  -V --print-version [arg]    Print version number for specified package (Example: -V mpich).
   -y --yes-to-all             Build non-interactively by assuming affirmative user responses.
   -z --disable-bootstrap      Disabling bootstrap build of GCC for speed when a recent GCC is already installed.