docs: Draft release notes for 3.1

docs/sources/tempo/configuration/parquet.md

@@ -12,7 +12,7 @@ This format is required for tags-based search as well as [TraceQL](../../traceql
 The columnar block format improves search performance and enables an ecosystem of tools, including [Tempo CLI](https://grafana.com/docs/tempo/<TEMPO_VERSION>/operations/tempo_cli/#analyse-blocks), to access the underlying trace data.
 
 Starting in Tempo 3.1, Tempo writes new blocks in `vParquet5` by default.
-Existing `vParquet4` and `vParquet3` blocks remain readable.
+Existing `vParquet4` and `vParquet3` blocks remain readable, but `vParquet3` writes and compaction are no longer supported.
 No data migration is required.
 
 ## Considerations
@@ -25,14 +25,15 @@ As soon as a block format version is enabled, Tempo starts writing data in that
 
 ## Block format versions
 
-{{< admonition type="warning" >}}
+Only Parquet-based formats are supported.
+
+### Removed and deprecated block formats
+
 The `v2` block format has been removed in Tempo 3.0.
-`vParquet3` is deprecated.
+
+`vParquet3` deprecation is enforced starting in Tempo 3.1: Tempo refuses to start if configured to write `vParquet3` blocks, and existing `vParquet3` blocks are no longer compacted.
 Tempo 3.x still reads existing `vParquet3` blocks.
 Write new blocks in `vParquet5` (default) or `vParquet4`.
-{{< /admonition >}}
-
-Only Parquet-based formats are supported.
 
 ### vParquet5