fill contribution guide in README.md

README.md

@@ -31,6 +31,7 @@ There are currently actions for:
 - **grayscaling** images
 - **filling transparent areas** in images with a given color
 - **converting** images to an A4 multi-page **PDF** document
+- **concatenating** PDF documents into one
 - **shrinking** PDF file sizes
 - **de/encrypting** arbitrary files with GPG
 - **finding big elements** in a folder
@@ -110,6 +111,32 @@ make install
 uca-apply update
 ```
 
-## Contribute
+## Troubleshooting
 
-If you would like to add translations or your own custom actions, take a look at the files under `share/thunar-custom-actions/system-uca`, add your changes there and then file a Pull Request. Alternatively, if you don't know how to do that or don't understand my system, you may also open a [new Issue here on GitHub](https://github.com/nobodyinperson/thunar-custom-actions/issues/new).
+#### There are no new actions after the installation!
+
+Close all `thunar` instances, run `thunar -q` from the terminal and then retry.
+
+## How to contribute
+
+Contributions are very welcome.
+
+### Translations
+
+This project uses **gettext** for localisation. The translation catalogues (`*.po`-files) can be found under the `locale` directory structured in the usual way. You may use the awesome translation program [poedit](https://github.com/vslavik/poedit) to edit them.
+
+If you wanted to add a whole new language, do the following:
+
+1. Clone the repository: `git clone https://github.com/nobodyinperson/thunar-custom-actions && cd thunar-custom-actions`
+2. Create an empty new catalogue for your language, (e.g. Czech `cs`): `mkdir -p locale/cs/LC_MESSAGES && touch locale/cs/LC_MESSAGES/thunar-custom-actions.po`.
+3. Configure the project with `./configure`.
+4. Now we have a `Makefile` to build the project with `make`.
+5. The newly created message catalogue can now be filled with e.g. [poedit](https://github.com/vslavik/poedit): `poedit locale/cs/LC_MESSAGES/thunar-custom-actions.po`.
+6. After filling the message catalogue you may build and install the project as usual.
+7. File a Pull Request on GitHub so I can include the new language into the code base.
+
+If you encounter problems with translations not being applied, re-add the `thunar-custom-actions`: `uca-apply remove && uca-apply update`
+
+### Custom actions
+
+If you want to see one of your own custom actions come with `thunar-custom-actions`, take a look at the files under `share/thunar-custom-actions/system-uca`, add your changes there and then file a Pull Request. Alternatively, if you don't know how to do that or don't understand my system, you may also open a [new Issue here on GitHub](https://github.com/nobodyinperson/thunar-custom-actions/issues/new).