Fix typo authentication.adoc

Author: 1993heqiang

docs/modules/ROOT/pages/servlet/saml2/login/authentication.adoc

@@ -337,7 +337,7 @@ Spring Security decrypts `<saml2:EncryptedAssertion>`, `<saml2:EncryptedAttribut
 The response decrypter is for decrypting encrypted elements of the `<saml2:Response>`, like `<saml2:EncryptedAssertion>`.
 The assertion decrypter is for decrypting encrypted elements of the `<saml2:Assertion>`, like `<saml2:EncryptedAttribute>` and `<saml2:EncryptedID>`.
 
-You can replace `OpenSaml4AuthenticationProvider`'s default decryption strategy with your own.
+You can replace `OpenSaml4AuthenticationProvider` 's default decryption strategy with your own.
 For example, if you have a separate service that decrypts the assertions in a `<saml2:Response>`, you can use it instead like so:
 
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