Update docs/platforms/javascript/common/tracing/span-metrics/index.mdx

Co-authored-by: Alex Krawiec <[email protected]>

Author: codyde

docs/platforms/javascript/common/tracing/span-metrics/index.mdx

@@ -41,7 +41,7 @@ When adding metrics as span attributes:
 
 - Use consistent naming conventions (for example, `category.metric_name`)
 - Keep attribute names concise but descriptive
-- Use appropriate data types (string, number, boolean, or arrays of these types)
+- Use appropriate data types (string, number, boolean, or (non-mixed) arrays of these types)
 
 ## Creating Dedicated Metric Spans