Adds definition of time series data (#225)

* Adds definition on time series data

* Adds definition to Ingest your data page

* Update serverless/pages/manage-your-project.asciidoc

Co-authored-by: shainaraskas <[email protected]>

* Update serverless/pages/ingest-your-data.asciidoc

Co-authored-by: shainaraskas <[email protected]>

---------

Co-authored-by: shainaraskas <[email protected]>

Author: kosabogi

serverless/pages/ingest-your-data.asciidoc

@@ -33,6 +33,11 @@ You can use these specialized tools to add general content to {es} indices:
 
 Time series, or timestamped data, describes data that changes frequently and "flows" over time, such as stock quotes, system metrics, and network traffic data.
 
+[NOTE]
+====
+Time series data refers to any document in standard indices or data streams that includes the `@timestamp` field.
+====
+
 You can use these specialized tools to add timestamped data to {es} data streams:
 
 * <<elasticsearch-ingest-data-through-beats,{beats}>>

serverless/pages/manage-your-project.asciidoc

@@ -36,6 +36,11 @@ The total volume of search-ready data is the sum of the following:
 . The volume of non-time series project data
 . The volume of time series project data included in the Search Boost Window
 
+[NOTE]
+====
+Time series data refers to any document in standard indices or data streams that includes the `@timestamp` field. This field must be present for data to be subject to the Search Boost Window setting.
+====
+
 Each project type offers different settings that let you adjust the performance and volume of search-ready data, as well as the features available in your projects.
 
 [discrete]