processor_labels: Use SHA-256 instead of SHA-1

This is because using hash algorithm is actually SHA-256.

Signed-off-by: Hiroshi Hatake <[email protected]>

pipeline/processors/labels.md

@@ -15,7 +15,7 @@ Note that processors and this specific component can only be enabled using the n
 | insert  | Insert a new key with a value into metrics. The key-value pair is required. |
 | upsert  | Upsert a specific key with a value, the `upsert` operation will try to update the value of the key. If the key does not exist, the key will be created. The key-value pair is required. |
 | delete  | Delete a key from the labels of metrics. The key-value pair is required. |
-| hash    | Replace the key value with a hash generated by the SHA-1 algorithm from the specified label name, the binary value generated is finally set as an hex string representation. |
+| hash    | Replace the key value with a hash generated by the SHA-256 algorithm from the specified label name, the binary value generated is finally set as an hex string representation. |
 
 
 #### Update example