Update install troubleshooting tips on MacOS

[kunalghosh]

Adds troubleshooting tips when installing dscribe on latest MacOS on apple-silicon.

The first include fixes:

In file included from dscribe/ext/acsf.cpp:1:
      dscribe/ext/acsf.h:4:10: fatal error: unordered_map: No such file or directory
          4 | #include <unordered_map>
            |          ^~~~~~~~~~~~~~~

and the second include fixes:

In file included from /Users/ghoshk1/Workspace/Homebrew/include/c++/13/unordered_map:34,
                       from dscribe/ext/acsf.h:4,
                       from dscribe/ext/acsf.cpp:1:
      /Users/ghoshk1/Workspace/Homebrew/include/c++/13/bits/requires_hosted.h:31:10: fatal error: bits/c++config.h: No such file or directory
         31 | #include <bits/c++config.h>