add change log

.chloggen/add_default_metadata_key_batch_processor.yaml

@@ -0,0 +1,15 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+# The name of the component, or a single word describing the area of concern, (e.g. agent, clusterReceiver, gateway, operator, chart, other)
+component: template
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: add default metadata key for token to batch processor
+# One or more tracking issues related to the change
+issues: []
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Add default metadata key for token to batch processor.
+  This will allow the token to be retrieved from the context. When SAPM is deprecated and
+  OTLP used, this will be the normal mode of operation.