Fix typo in ETL pipeline document (#2626)

Signed-off-by: Yanming Zhou <zhouyanming@gmail.com>

Author: quaff

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/etl-pipeline.adoc

@@ -12,7 +12,7 @@ The ETL pipelines creates, transforms and stores `Document` instances.
 
 image::spring-ai-document1-api.jpg[Spring AI Message API, width=400, align="center"]
 
-The `Document` class contains text, metadata and optionally additionall media types like images, audio and video.
+The `Document` class contains text, metadata and optionally additional media types like images, audio and video.
 
 There are three main components of the ETL pipeline,