Update data frame docs (#23983)

docs/sources/plugins/developing/dataframe.md

@@ -10,9 +10,11 @@ draft = true
 
 ## Introduction to data frames
 
-Grafana supports a variety of different data sources, each with its own data model. To make this possible, Grafana consolidates the query results from each of these data sources into one, unified data structure called _data frames_.
+Grafana supports a variety of different data sources, each with its own data model. To make this possible, Grafana consolidates the query results from each of these data sources into one unified data structure called a _data frame_.
 
-Data frames were introduced in Grafana 7.0 to replace the Time series and Table structures with a more generic data structure that can support a wider range of data types.
+The data frame structure is a concept that's borrowed from data analysis tools like the [R programming language](https://www.r-project.org), and [Pandas](https://pandas.pydata.org/).
+
+> Data frames are available in Grafana 7.0+, and replaced the Time series and Table structures with a more generic data structure that can support a wider range of data types.
 
 This document gives an overview of the data frame structure, and of how data is handled within Grafana.
 
@@ -60,6 +62,18 @@ Each field has three values, and each value in a field must share the same type.
 
 One restriction on data frames is that all fields in the frame must be of the same length to be a valid data frame.
 
+#### Field configuration
+
+Each field in a data frame contains optional information about the values in the field, such as units, scaling, and so on.
+
+By adding field configurations to a data frame, Grafana can configure visualizations automatically. For example, you could configure Grafana to automatically set the unit provided by the data source.
+
+### Transformations
+
+Along with the type information, field configs enables _data transformations_ within Grafana.
+
+A data transformation is any function that accepts a data frame as input, and returns another data frame as output. By using data frames in your plugin, you get a range of transformations for free.
+
 ### Data frames as time series
 
 A data frame with at least one time field is considered a _time series_.
@@ -113,7 +127,7 @@ Dimensions: 2 fields by 2 rows
 
 The wide format can typically be used when multiple time series are collected by the same process. In this case, every measurement is made at the same interval and will therefore share the same time values.
 
-### Long format
+#### Long format
 
 Some data sources return data in a _long_ format (also called _narrow_ format). This is common format returned by, for example, SQL databases.