docs: add FAQ section to the developer guide

docs/developer_guide.md

@@ -88,4 +88,11 @@ In some of the tests:
 
 When the `testdata` folder needs to be updated, it can be manually regenerated by setting `update_testdata` to `True` in `conftest.py` and running the tests.
 
-Whenever the `testdata` folder is generated, the files should be reviewed manually to ensure everything works as expected.
+Whenever the `testdata` folder is generated, the files should be reviewed manually to ensure everything works as expected.
+
+
+## Frequently Asked Questions (FAQ)
+
+### How can I add a new social network to RenderCV?
+
+To be answered.