doc: expand troubleshooting section

Update the troubleshooting section with regards to memory requirements and potential errors.

This error specifically happened to me on an Ubuntu host with 2GB of RAM which wasn't enough and g++ error'ed during Node.js compilation step.

BUILDING.md

@@ -594,6 +594,10 @@ rebuild may take a lot more time than previous builds. Additionally,
 ran `./configure` with non-default options (such as `--debug`), you will need
 to run it again before invoking `make -j4`.
 
+If you received the error `nodejs g++ fatal error compilation terminated cc1plus`
+during compilation, this is likely a memory issue and you should either provide
+more RAM or create swap space to accommodate toolchain requirements.
+
 ### Windows
 
 #### Tips