doc[developer-guide]: added overview of folder structure

docs/How_to_contribute.md

@@ -64,3 +64,25 @@ A new version number shall be determined as follows:
 * Release adds a major new feature or modifies any interface (for example by modifying the format of input or output data) in such a way that it is <b>not fully compatible</b> with the previous version anymore.
     * ==> Increase first digit by `1`.
     * ==> Set remaining digits to `0`.
+
+# Developer hints
+## Output folder structure
+All tools developed as part of the DiscoPop Project make use of the following folder structure:
+```
+- project root/
+ - .discopop/
+  - common_data/
+   - FileMapping.txt
+  - <tool_1>/
+    - tool_1 output files
+    - private/
+     - tool_1 intermediate files
+  - <tool_2>/
+    - ...
+  - ...
+```
+, where no data should be stored / created outside the `.discopop` folder in order to keep the users build directory as clean as possible.
+Files which are read by different tools, e.g. the `FileMapping.txt`, shall be stored in the `.discopop/common_data` folder.
+Each tool may create a folder. In case data from these files is required by another tool, think about how to encode the information in a easy-to-use and structured format, preferrably JSON. If possible, please do not rely on exporting to simple `.txt` files as parsing adds a potential point of failure.
+Output data for use by other tools should be stored in the folder of the creating tool. Intermediate files may be stored in a folder named `private` and shall not be used by other tools.
+Analysis tools, like pattern detection scripts etc. shall be structured in such a way, that a execution from within the `.discopop` folder is intended.