docs(reporting): describe how Detail and Tabular blocks lay out screenshots and code

docs/content/metrics_reports/reports/PRO__report_builder.md

@@ -85,6 +85,8 @@ The difference is presentation: a **Tabular** block lays the records out as a ta
 
 Fields render in the order they are listed. Selecting a field adds it to the end of the list, and the **Fields** section of the block editor shows the selection as a numbered list you can rearrange: drag a field by its handle, or use the arrow buttons to move it up or down. Removing a field from that list deselects it. Columns in a Tabular block, and the label and value pairs in a Detail block, follow this order when the report is generated.
 
+In a Detail block, a markdown field with content takes the full width of the page, and the other fields sit two to a row. Screenshots in a markdown field, such as those added to a Finding's **Steps to Reproduce**, scale down to fit the page, and code blocks wrap. A record too tall for one page continues on the next page. A Tabular block scales each screenshot to the width of its column, so use a Detail block when readers need to read the screenshots.
+
 On the Organization, Asset, Engagement, Test and Finding entities, the **Fields** and **Order By** pickers list their fields under the same headings as that entity's list page uses for **Add Filter**, in the same order: on Finding, for example, Finding, Threat Intel, Asset, Engagement and Test, Dates and People. A search in the **Fields** picker shows only the headings that still hold a matching field. The headings only arrange the picker: the numbered list under it, and the generated report, keep the order you set. The other entities list their fields without headings.
 
 The records are sorted by the block's **Order By** field, in the **Order Direction** you choose. A block saved with a sort field its entity no longer offers (one renamed since the block was built, say) is generated unsorted rather than failing the report, and the server log names the block and the field.