Document --host-runner argument as alternative to nvm

Author: hoodmane

getting-started/setup-building.rst

@@ -541,7 +541,10 @@ Once built for a given Emscripten version, they will not be rebuilt on
 subsequent runs unless there is a change in the version or build script for the
 dependency.
 
-It is assumed that nvm_ is installed in `${HOME}/.nvm`.
+It is assumed that nvm_ is installed in ``${HOME}/.nvm``. If you don't have nvm
+installed or don't want to use it, you can pass ``--host-runner node`` to the
+``build`` command. The argument should either be the name of an executable that
+can be found on the ``PATH`` or a relative or absolute path to an executable.
 
 If you omit the ``EMSDK_CACHE`` environment variable, the build script will
 assume that the current environment has the Emscripten tools available. You are