Updated doc about chunks storage deprecation (#4294)

Signed-off-by: Marco Pracucci <[email protected]>

Author: pracucci

docs/configuration/arguments.md

@@ -11,6 +11,8 @@ Cortex has evolved over several years, and the command-line options sometimes re
 
 Duration arguments should be specified with a unit like `5s` or `3h`. Valid time units are "ms", "s", "m", "h".
 
+**Warning: some of the following config options apply only to chunks storage, which has been deprecated. You're encouraged to use the [blocks storage](../blocks-storage/_index.md).**
+
 ## Querier
 
 - `-querier.max-concurrent`

docs/configuration/config-file-reference.md

@@ -2708,7 +2708,7 @@ chunk_tables_provisioning:
 The `storage_config` configures where Cortex stores the data (chunks storage engine).
 
 ```yaml
-# The storage engine to use: chunks or blocks.
+# The storage engine to use: chunks (deprecated) or blocks.
 # CLI flag: -store.engine
 [engine: <string> | default = "chunks"]
 

pkg/chunk/storage/factory.go

@@ -111,7 +111,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	cfg.Swift.RegisterFlags(f)
 	cfg.GrpcConfig.RegisterFlags(f)
 
-	f.StringVar(&cfg.Engine, "store.engine", "chunks", "The storage engine to use: chunks or blocks.")
+	f.StringVar(&cfg.Engine, "store.engine", "chunks", "The storage engine to use: chunks (deprecated) or blocks.")
 	cfg.IndexQueriesCacheConfig.RegisterFlagsWithPrefix("store.index-cache-read.", "Cache config for index entry reading. ", f)
 	f.DurationVar(&cfg.IndexCacheValidity, "store.index-cache-validity", 5*time.Minute, "Cache validity for active index entries. Should be no higher than -ingester.max-chunk-idle.")
 }