[pitivi] docs: Remove the easy way of setting the dev env

[Alexandru Băluț <alexbalut src gnome org>]

commit 034ccfb3706017e3bcf9b688c0fb6a39e524a938
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Sat Feb 8 01:30:11 2020 +0100

    docs: Remove the easy way of setting the dev env
    
    It's difficult to run the unittests in Builder, as described in the
    removed text. We can add it back when it works better.

 docs/HACKING.md | 71 +++++++++++++++------------------------------------------
 1 file changed, 19 insertions(+), 52 deletions(-)
---
diff --git a/docs/HACKING.md b/docs/HACKING.md
index c258d08f..81f14ae8 100644
--- a/docs/HACKING.md
+++ b/docs/HACKING.md
@@ -4,53 +4,20 @@ short-description: Using the Pitivi development environment
 
 # Hacking on Pitivi
 
-There are two ways to set up a flatpak sandbox with all the
-dependencies required to run and develop Pitivi. We recommend
-the advanced way, but if you want something quick, go ahead with
-the easy way.
+To develop Pitivi on Linux you need to set up a development environment,
+as described below. For [other platforms](crossplatform.md), get in
+touch with us.
 
-## The easy way
+By setting up a development environment, you create a
+[flatpak](https://flatpak.org) sandbox containing all the Pitivi
+dependencies. The sandbox is then used to run Pitivi and the unittests,
+without messing your system.
 
-The easy way to setup the development environment is to follow the
-[GNOME Newcomers guide](https://wiki.gnome.org/Newcomers/).
+Start by installing **both** [flatpak](http://flatpak.org/getting.html)
+and `flatpak-builder` on your system.
 
-This implies using GNOME Builder to manage the dependencies sandbox.
-
-Clone the `https://gitlab.gnome.org/GNOME/pitivi.git` git repository
-in GNOME Builder.
-
-To run the unittests, click in Builder: Unittests > pitivi > Pitivi unit tests.
-Make sure they all pass, or tell us about any failures.
-
-To be able to use our pre-commit git hook, run:
-
-```
-$ cd ~/Projects/pitivi
-$ ln -s ../../pre-commit.hook .git/hooks/pre-commit
-```
-
-When creating commits, for the pre-commit git hook to work properly
-it has to run in the sandbox. This is possible only by running `git`
-in a Build Terminal in GNOME Builder. You might want to
-`export EDITOR=nano` if you get "error: unable to start editor 'vi'"
-when you have to enter a commit message.
-
-
-## Setting up the advanced development environment
-
-> NOTE: This way of setting the development environment is sensibly more complex
-> but also more flexible than the one for newcomers. If you are a  beginner
-> or if you usually use [GNOME Builder](https://wiki.gnome.org/Apps/Builder)
-> as your main IDE, follow, as previously advised, the
-> [GNOME Newcomers guide](https://wiki.gnome.org/Newcomers/)
-
-The official way of getting your environment up and running is by using
-[flatpak](http://flatpak.org/). For this you need to
-[install flatpak](http://flatpak.org/getting.html) on your system,
-along with flatpak-builder. Note flatpak-builder might be provided by an
-additional package on some distributions (such as Archlinux).
-
-Create a development environment folder and get the [Pitivi source 
code](http://gitlab.gnome.org/GNOME/pitivi) into it:
+Create a development environment folder and get the [Pitivi source
+code](http://gitlab.gnome.org/GNOME/pitivi) into it:
 
 ```
 $ mkdir pitivi-dev
@@ -58,7 +25,9 @@ $ cd pitivi-dev
 $ git clone https://gitlab.gnome.org/GNOME/pitivi.git
 ```
 
-Whenever you want to hack on Pitivi, enter the development environment:
+Whenever you want to hack on Pitivi, start a new terminal and enter the
+development environment:
+
 ```
 $ cd pitivi-dev/pitivi && source bin/pitivi-env
 -> Setting up the prefix for the sandbox...
@@ -68,19 +37,17 @@ Running in sandbox: echo Prefix ready
 Prefix ready
 ```
 
-This can take a while when creating the sandbox from scratch. Note the
-prompt changes:
+When creating the sandbox from scratch it can take up to a few hours,
+depending on your internet connection speed and the CPU. Note the prompt
+changes:
+
 ```
 (ptv-flatpak) $
 ```
 
 By entering the development environment, you get:
 - a [Flatpak sandbox](http://docs.flatpak.org/en/latest/working-with-the-sandbox.html)
-for the dependencies, in `pitivi-dev/pitivi-prefix`
-- a [Python virtual environment](http://docs.python-guide.org/en/latest/dev/virtualenvs/)
-with development tools, such as
-[pre-commit](http://pre-commit.com),
-in `pitivi-dev/pitivi/build/flatpak/pyvenv`
+with dependencies and some development tools, in `pitivi-dev/pitivi-prefix`
 - the [Meson build directory](http://mesonbuild.com/Quick-guide.html),
 in `pitivi-dev/pitivi/mesonbuild`
 - some aliases for the build tools, such as `ninja`, so they are executed in the sandbox.