message: added FAQ entry about using multiple source files - fixes
diff: - [**Why do I get compiler errors in STL headers when including the doctest header?**](#why-do-i-get-compiler-errors-in-stl-headers-when-including-the-doctest-header)
  - [**Can different versions of the framework be used within the same binary (executable/dll)?**](#can-different-versions-of-the-framework-be-used-within-the-same-binary-executabledll)
  - [**Why is doctest using macros?**](#why-is-doctest-using-macros)
  +- [**How to use with multiple files?**](#how-to-use-with-multiple-files)
  ### How is **doctest** different from Catch?
  @@ -167,6 +168,10 @@ Currently no. Single header libraries like [**stb**](https://github.com/nothings
  Aren't they evil and not *modern*? - Check out the answer Phil Nash gives to this question [**here**](http://accu.org/index.php/journals/2064) (the creator of [**Catch**](https://github.com/catchorg/Catch2)).
  +### How to use with multiple files?
  +
  +All you need to do is define either [**```DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN```**](configuration.md#doctest_config_implement_with_main) or [**```DOCTEST_CONFIG_IMPLEMENT```**](configuration.md#doctest_config_implement) in only ONE of the source files just before including the doctest header - in all other source files you just include the header and use the framework. The difference between the two is that one of them provides a `main()` entry point - for more info on that please refer to [`The main() entry point`](main.md).
  +
  ---------------
  [Home](readme.md#reference)
  