Doc: running from source and building on Linux (#5881)

* CI: make the comment in 'Build' more verbose

* Doc: add Linux running from source and build instructions

* Doc: fix name in running from source on Linux

* Update docs/running from source.md

Co-authored-by: qwint <qwint.42@gmail.com>

---------

Co-authored-by: qwint <qwint.42@gmail.com>

.github/workflows/build.yml

@@ -1,4 +1,5 @@
-# This workflow will build a release-like distribution when manually dispatched
+# This workflow will build a release-like distribution when manually dispatched:
+# a Windows x64 7zip, a Windows x64 Installer, a Linux AppImage and a Linux binary .tar.gz.
 
 name: Build
 

docs/running from source.md

@@ -52,6 +52,32 @@ Recommended steps
 Refer to [Guide to Run Archipelago from Source Code on macOS](../worlds/generic/docs/mac_en.md).
 
 
+## Linux
+
+If your Linux distribution ships a compatible Python version (see [General](#general)) and pip, you can use that,
+otherwise you may need to install Python from a 3rd party. Refer to documentation of your Linux distribution.
+
+Installing a C compiler is usually optional. The package is typically named `gcc`, sometimes another package with the
+base build tools may be required, i.e. `build-essential` (Debian/Ubuntu) or `base-devel` (Arch).
+
+After getting the source code, it is strongly recommended to create a
+[venv](https://docs.python.org/3/tutorial/venv.html) (Virtual Environment)
+by hand or using an IDE, such as PyCharm, because Archipelago requires specific versions of Python packages.
+
+Run `python ModuleUpdate.py` in the project root to install packages, run `python Launcher.py` to run the Launcher.
+
+### Building
+
+Builds contain (almost) all dependencies to run Archipelago on any Linux distribution that is as new or newer than the
+one it was built on. Beware that currently only the oldest Ubuntu LTS available in GitHub actions is supported for that.
+This means the easiest way to generate a build is by running the `Build` action from GitHub actions instead of building
+locally. If you still want to, e.g. for local testing, you can by running
+
+`python setup.py build_exe` to generate a binary distribution of Archipelago in `build/`. Or to generate an AppImage
+first generate the binary distribution and then run `python setup.py bdist_appimage` to populate `dist/`. You need to
+put an `appimagetool` into the directory you run the command from, rename it to `appimagetool` and make it executable.
+
+
 ## Optional: A Link to the Past Enemizer
 
 Only required to generate seeds that include A Link to the Past with certain options enabled. You will receive an