Add versioning section to readme and docs (#8582)

Author: flobernd

README.md

@@ -10,11 +10,20 @@ or
 **for a free trial of Elastic Cloud**.
 
 The .NET client for Elasticsearch provides strongly typed requests and responses
- for Elasticsearch APIs. It delegates protocol handling to the 
- [Elastic.Transport](https://github.com/elastic/elastic-transport-net) library,
+ for Elasticsearch APIs. It delegates protocol handling to the
+[Elastic.Transport](https://github.com/elastic/elastic-transport-net) library,
  which takes care of all transport-level concerns (HTTP connection establishment
  and pooling, retries, etc.).
 
+## Versioning
+
+The *major* and *minor* version parts of the Elasticsearch .NET client are dictated by the version of the Elasticsearch server.
+
+> [!WARNING]
+> This means that the Elasticsearch .NET client **does not** strictly follows semantic versioning!
+>
+> Although we try to avoid this as much as possible, it can happen that a *minor* or even *patch* version contains breaking changes (see also: [breaking changes policy](https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/breaking-changes-policy.html)). Please always check the [release notes](https://github.com/elastic/elasticsearch-net/releases) before updating the client package.
+
 ## Compatibility
 
 Language clients are **forward compatible**: