Update documentation to include changes to default root path

Author: CharlieTLe

docs/blocks-storage/querier.md

@@ -490,7 +490,7 @@ blocks_storage:
   filesystem:
     # Local filesystem storage directory.
     # CLI flag: -blocks-storage.filesystem.dir
-    [dir: <string> | default = ""]
+    [dir: <string> | default = "/"]
 
   # This configures how the querier and store-gateway discover and synchronize
   # blocks stored in the bucket.

docs/blocks-storage/store-gateway.md

@@ -614,7 +614,7 @@ blocks_storage:
   filesystem:
     # Local filesystem storage directory.
     # CLI flag: -blocks-storage.filesystem.dir
-    [dir: <string> | default = ""]
+    [dir: <string> | default = "/"]
 
   # This configures how the querier and store-gateway discover and synchronize
   # blocks stored in the bucket.

docs/configuration/config-file-reference.md

@@ -768,7 +768,7 @@ swift:
 filesystem:
   # Local filesystem storage directory.
   # CLI flag: -alertmanager-storage.filesystem.dir
-  [dir: <string> | default = ""]
+  [dir: <string> | default = "/"]
 
 # The configstore_config configures the config database storing rules and
 # alerts, and is used by the Cortex alertmanager.
@@ -1047,7 +1047,7 @@ swift:
 filesystem:
   # Local filesystem storage directory.
   # CLI flag: -blocks-storage.filesystem.dir
-  [dir: <string> | default = ""]
+  [dir: <string> | default = "/"]
 
 # This configures how the querier and store-gateway discover and synchronize
 # blocks stored in the bucket.
@@ -4728,7 +4728,7 @@ swift:
 filesystem:
   # Local filesystem storage directory.
   # CLI flag: -ruler-storage.filesystem.dir
-  [dir: <string> | default = ""]
+  [dir: <string> | default = "/"]
 
 # The configstore_config configures the config database storing rules and
 # alerts, and is used by the Cortex alertmanager.
@@ -5015,7 +5015,7 @@ swift:
 filesystem:
   # Local filesystem storage directory.
   # CLI flag: -runtime-config.filesystem.dir
-  [dir: <string> | default = ""]
+  [dir: <string> | default = "/"]
 ```
 
 ### `s3_sse_config`