Add Mölndal source (#2332)

* Add Mölndal source

* reformatting

---------

Co-authored-by: 5ila5 <5ila5@users.noreply.github.com>

doc/source/molndal_se.md

@@ -0,0 +1,34 @@
+# Mölndal
+
+This is a waste collection schedule integration for the Mölndal.
+Mölndal is using EDPEvent but does not allow for address search.
+
+## Configuration via configuration.yaml
+
+```yaml
+waste_collection_schedule:
+  sources:
+    - name: molndal_se
+      args:
+        facility_id: FACILITY_ID
+```
+
+### Configuration Variables
+
+**facility_id**  
+*(number) (required)*
+
+## Examples
+
+```yaml
+waste_collection_schedule:
+  sources:
+    - name: molndal_se
+      args:
+        facility_id: 105000
+```
+
+## How to get the correct facility id
+
+Your facility_id (Anläggning) can be found on invoices from Mölndals stad or
+by the [Mölndals stad e-tjänst](https://etjanst.molndal.se/oversikt/overview/720).