Rename beforeSendSpans to beforeSendSpan (#15447)

Author: cleptric

develop-docs/sdk/telemetry/spans/scrubbing-data.mdx

@@ -10,7 +10,7 @@ title: Scrubbing data
   This document uses key words such as "MUST", "SHOULD", and "MAY" as defined in [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt) to indicate requirement levels.
 </Alert>
 
-## Scrubbing data with `beforeSendSpans`
+## Scrubbing data with `beforeSendSpan`
 
 This callback MUST NOT allow the removal of any spans from the span tree.
 It receives a deep copy of all spans in the span tree and their attributes.
@@ -28,4 +28,4 @@ It receives a deep copy of all spans in the span tree and their attributes.
 ```
 
 Users MAY mutate any exposed properties to perform sanitation on sensitive data or PII.
-The return value of `beforeSendSpans` MUST be merged with the original span tree prior to emission.
+The return value of `beforeSendSpan` MUST be merged with the original span tree prior to emission.