message: More submodule options in the howto
diff: @@ -17,7 +17,7 @@ You can see your fork at https://github.com/LOGIN/gudhi-devel
  ## Create a local clone on your computer
  ```bash
  -git clone https://github.com/LOGIN/gudhi-devel.git
  +git clone --recurse-submodules https://github.com/LOGIN/gudhi-devel.git
  ```
  This creates a directory gudhi-devel, which you are free to move around or rename. For the following, change to that directory:
  @@ -25,16 +25,14 @@ This creates a directory gudhi-devel, which you are free to move around or renam
  cd gudhi-devel
  ```
  -When you clone the repository, you also need to download the *submodules*.
  -
  ## Submodules
  -Hera, used for Wasserstein distance, is available on an external git repository. To download it:
  +When you clone the repository, you also need to download the *submodules*. This is done automatically thanks to `--recurse-submodules`.
  +If you forgot this option, you can still download them with
  ```bash
  git submodule update --init
  ```
  -[gudhi-deploy](https://github.com/GUDHI/gudhi-deploy) is used for Continuous Integration python
  -requirements and will also be downloaded by the above command.
  +The submodules appear in the `ext/` subdirectory. There are currently 2, [Hera](https://github.com/anigmetov/hera) for distances between persistence diagrams, and [gudhi-deploy](https://github.com/GUDHI/gudhi-deploy) for Continuous Integration.
  ## Configuring a remote for a fork
  ```bash
  @@ -68,6 +66,11 @@ It is safe, it will not mess with your files.
  git submodule sync
  git submodule update --init
  ```
  +You can configure `git` to do this automatically with
  +```bash
  +git config submodule.recurse true
  +```
  +(add `--global` if you want it to apply to other projects as well)
  ## Create a branch, based on the current master
  ```bash
  