fix: set default add index concurrency to 8 (#1829)

* fix: set default add index concurrency to 8

* Update docs

Author: ischasny

Diff for: node/config/def.go

@@ -24,7 +24,7 @@ const (
 var MaxTraversalLinks uint64 = 32 * (1 << 20)
 
 const (
-	DefaultAddIndexConcurrency = 1
+	DefaultAddIndexConcurrency = 8
 )
 
 func init() {

Diff for: node/config/doc_gen.go

@@ -419,7 +419,7 @@ type LocalIndexDirectoryConfig struct {
 	// is in the piece, and adds the index to the local index directory.
 	ParallelAddIndexLimit int
 	// AddIndexConcurrency sets the number of concurrent tasks that each add index operation is split into.
-	// This setting is usefull to better utilise bandwidth between boostd and boost-data. The default value is 4.
+	// This setting is usefull to better utilise bandwidth between boostd and boost-data. The default value is 8.
 	AddIndexConcurrency int
 	// The port that the embedded local index directory data service runs on.
 	// Set this value to zero to disable the embedded local index directory data service