ModflowAPI does not properly initialize using the current MacOS instructions and Mamba

[mmorphew]

When using the current instructions for installing Modflow6 on MacOS, users are instructed to link their Modflow6 shared library to their bin folder, but the ModflowAPI appears to search the lib library in the conda environment instead. The final ln command at the end of the build parallel mf6 page should instead be written as:

ln ./bin/libmf6.dylib $CONDA_PREFIX/lib/libmf6.dylib

Or if the bin link is needed for other applications, then mac users should perhaps link to both their lib and bin directories in their conda environment.