readme: note that redaction is not supported in the browser (#671)

docs/redaction.md

@@ -1,5 +1,7 @@
 # Redaction
 
+> Redaction is not supported in the browser [#670](https://github.com/pinojs/pino/issues/670)
+
 To redact sensitive information, supply paths to keys that hold sensitive data
 using the `redact` option:
 
@@ -129,5 +131,3 @@ It's extremely important that path strings do not originate from user input.
 The `fast-redact` module uses a VM context to syntax check the paths, user input
 should never be combined with such an approach. See the [`fast-redact` Caveat](https://github.com/davidmarkclements/fast-redact#caveat)
 and the [`fast-redact` Approach](https://github.com/davidmarkclements/fast-redact#approach) for in-depth information.
-
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