Docs/SSE: Misc updates and corrections (#35882)

* Docs/SSE: Misc updates and coorections

* Update docs/sources/panels/expressions.md

Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>

Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>

docs/sources/panels/expressions.md

@@ -11,9 +11,9 @@ Server-side expressions allow you to manipulate data returned from queries with
 
 ## Using expressions
 
-The primary use case for expressions is for the upcoming next version of Grafana alerting. Like alerting, processing is done server-side, so expressions can operate without a browser session. However, expressions can be used with backend data sources and visualization as well.
+Expressions are primarily used by the new [Grafana 8 alerts]({{< relref "../alerting/unified-alerting/" >}}). The processing is done server-side, so expressions can operate without a browser session. However, expressions can also be used with backend data sources and visualization.
 
-> **Note:** Expressions do not work with current Grafana alerting.
+> **Note:** Expressions do not work with legacy dashboard alerts.
 
 > **Note:** Expressions do not work with dashboard variables.
 
@@ -32,7 +32,7 @@ To reference the output of an individual expression or a data source query in an
 Expressions work with two types of data.
 
 - A collection of time series.
-- A collection of numbers, where each collection could be a single series or single number.
+- A collection of numbers, where each item in the collection is a single number.
 
 Each collection is returned from a single data source query or expression and represented by the RefID. Each collection is a set, where each item in the set is uniquely identified by it dimensions which are stored as [labels]({{< relref "../basics/timeseries-dimensions.md#labels" >}}) or key-value pairs.