558 improve capabilities handling (#562)

* add handling for missing capabilities file

* improve documentation

* Update doc/user/installation.rst

doc/dev/repository.rst

@@ -0,0 +1,17 @@
+.. _developer-manual-repository:
+
+Repository
+==========
+
+:Last Reviewed: 2023-09-05
+
+This project uses subprojects and retrieves its versioning
+information from version control.
+Therefore it is crucial that you follow these rules when
+working with the project (e.g. for packaging a
+development version).
+
+* Make sure that the git project is complete. A call to git status for example should succeed.
+* Make sure that you have checked out all available subprojects.
+* Proper initialization of submodules can be ensured with ``git submodule update --init --recursive``
+

doc/index.rst

@@ -53,6 +53,7 @@ developers of this library.
 
    dev/release-process
    dev/contributing
+   dev/repository
    dev/changelog
    dev/todo
 

doc/user/installation.rst

@@ -29,6 +29,20 @@ The following installation options exist:
  * `win32`: install packages required for win32 printing (only Windows)
  * `cups`: install packages required for CUPS printing
 
+Other installation methods
+--------------------------
+Officially, no other installation methods are supplied.
+
+If you want to install nevertheless from another source,
+please make sure that you have received the correct package
+and that the capabilities data is properly integrated.
+When packaging from source please read the developer
+information in :ref:`developer-manual-repository`.
+
+If your packaging method breaks the resource system from setuptools,
+it might be necessary to supply the path to the capabilities file:
+:ref:`advanced-usage-change-capabilities-profile`.
+
 Setup udev for USB-Printers
 ---------------------------
 1. Get the *Product ID* and *Vendor ID* from the lsusb command