refactor: converted config.json to config.yaml and passes all tests. #19.

examples/config.yaml

+concept_sets:
+  version: "v1.0.1"
+  omop:
+    vocabulary_id: "ACMC_Example"
+    vocabulary_name: "ACMC example phenotype"
+    vocabulary_reference: "https://git.soton.ac.uk/meldb/concepts-processing/-/tree/main/examples"
+  concept_set:
+    - concept_set_name: "ABDO_PAIN"
+      concept_set_status: "AGREED"
+      metadata: {}
+
+codes:
+  - folder: "clinical-codes-org"
+    description: "Downloaded 16/11/23"
+    files:
+      - file: "Symptom code lists/Abdominal pain/res176-abdominal-pain.csv"
+        columns:
+          read2: "code"
+          metadata:
+            - "description"
+        concept_set:
+          - "ABDO_PAIN"
+