[community.software.sil.org] Start a topic about offline word collection

After we have a stable release of the Linux installer.

Add a new topic (to be pinned) about options for offline The Combine usage (e.g., NUC) to https://community.software.sil.org/c/combine/46

Then Danny/Jason can add a link to that topic in https://software.sil.org/thecombine/#downloads