clarify GET/Activites endpoint and split into separate sentence

docs/howto_guides/api_gui.md

@@ -57,7 +57,7 @@ If the data object identifier is known, the metadata can be retrieved using the
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 ![find get activities](../_static/images/howto_guides/api_gui/find_get_activities.png)
-The `GET /activities` endpoint is a general way to fetch metadata about various activities (e.g. metagenome assembly, natural organic matter analysis, library preparation, etc.). Any "slot" (a.k.a. attribute) for [WorkflowExecutionActivty](https://microbiomedata.github.io/nmdc-schema/WorkflowExecutionActivity/) or [PlannedProcess](https://microbiomedata.github.io/nmdc-schema/PlannedProcess/)  may be used in the filter and sort parameters, including attributes for subclasses of `WorkflowExecutionActvity` and `PlannedProcess`, such as slots used in the `MetabolomicsAnalysisActivity` or `Extraction` class among others.<br/>
+The `GET /activities` endpoint is a general way to fetch metadata about various activities (e.g. metagenome assembly, natural organic matter analysis, library preparation, etc.). Any "slot" (a.k.a. attribute) for [WorkflowExecutionActivty](https://microbiomedata.github.io/nmdc-schema/WorkflowExecutionActivity/) or [PlannedProcess](https://microbiomedata.github.io/nmdc-schema/PlannedProcess/) classes may be used in the filter and sort parameters, including attributes for subclasses of `WorkflowExecutionActvity` and `PlannedProcess`. For example, attributes used in subclasses such as, [MetabolomicsAnalysisActivity](https://microbiomedata.github.io/nmdc-schema/MetabolomicsAnalysisActivity/) (subclass of `WorkflowExecutionActivity`) or (Extraction)[https://microbiomedata.github.io/nmdc-schema/Extraction/] (subclass of `PlannedProcess`), can be used as input criteria for the filter and sort parameters of this endpoint.<br/>
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 ![find get activities by activity id](../_static/images/howto_guides/api_gui/find_get_activities_activity_id.png)