message: docs: Add info about required npm version
  Npm 3.10 version is required to install dev tools correctly on Linux.
  Change-type: patch
diff: @@ -21,6 +21,7 @@ Developing
  - [Python 2.7](https://www.python.org)
  - [jq](https://stedolan.github.io/jq/)
  - [curl](https://curl.haxx.se/)
  +- [npm](https://www.npmjs.com/) (version 3.10)
  ```sh
  pip install -r requirements.txt
  