feat: adding docs for payment metadata (#124)

Co-authored-by: vacwmX <vacwm01@gmail.com>
Co-authored-by: ok300 <106775972+ok300@users.noreply.github.com>

snippets/python/src/metadata.py

@@ -0,0 +1,45 @@
+import breez_sdk
+
+def set_payment_metadata(sdk_services):
+    try: 
+        # ANCHOR: set-payment-metadata
+        sdk_services.set_payment_metadata("target-payment-hash", '{"myCustomValue":true}')    
+        # ANCHOR_END: set-payment-metadata
+    except Exception as error: 
+        # handle error
+        raise
+
+def filter_payment_metadata(sdk_services):
+    # ANCHOR: filter-payment-metadata
+    metadata_filters = [
+        breez_sdk.MetadataFilter("myCustomValue", "true")
+    ]
+
+    try:
+        sdk_services.list_payments(breez_sdk.ListPaymentsRequest(
+            metadata_filters = metadata_filters
+        ))
+    except Exception as error:
+        # handle error
+        raise
+    # ANCHOR_END: filter-payment-metadata
+
+    # ANCHOR: filter-payment-metadata-string
+    metadata_filters = [
+        breez_sdk.MetadataFilter("customerName", "\"Satoshi Nakamoto\""),
+        breez_sdk.MetadataFilter("customerName", json.dumps("Satoshi Nakamoto")),
+    ]
+    # ANCHOR_END: filter-payment-metadata-string
+
+    # ANCHOR: filter-payment-metadata-object
+    # This will *NOT* work
+    metadata_filters = [
+        breez_sdk.MetadataFilter("parent.nestedArray", "[1, 2, 3]")
+    ]
+
+    # Any of these will work
+    metadata_filters = [
+        breez_sdk.MetadataFilter("parent.nestedArray", "[1,2,3]"),
+        breez_sdk.MetadataFilter("parent.nestedArray", json.dumps([1,2,3], separators=(',', ':'))),
+    ]
+    # ANCHOR_END: filter-payment-metadata-object