Add version pinning guidance to installation section

Co-authored-by: llucax <[email protected]>

Author: Copilot

README.md

@@ -58,6 +58,12 @@ dependencies = [
 ]
 ```
 
+> [!NOTE]
+> We recommend pinning the dependency to the latest version for programs,
+> like `"frequenz-quantities == 1.0.0"`, and specifying a version range
+> spanning one major version for libraries, like `"frequenz-quantities >= 1.0.0, < 2"`.
+> We follow [semver](https://semver.org/).
+
 ## Documentation
 
 For more information on how to use this library and examples, please check the