message: Update the how_to_update_electron.md with the correct node-sass version
diff: @@ -40,7 +40,7 @@ Outside the Extraterm source tree, find some space and do:
  * `git clone --recursive https://github.com/sass/node-sass.git`
  * `cd node-sass`
  -* `git checkout v4.9.0` -- this should match the desired version of node-sass
  +* `git checkout v4.12.0` -- this should match the desired version of node-sass
  * `git submodule update --init --recursive`
  * `npm install`
  * `node ./node_modules/node-gyp/bin/node-gyp.js rebuild --target=5.0.6 --arch=x64 --dist-url=https://atom.io/download/atom-shell --verbose --libsass_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=` -- The `--target` option should match the new Electron version!
  