fix typo in S&P considerations

README.md

@@ -588,7 +588,7 @@ One important privacy consideration is that partitioned cookies must not be subj
 
 Another privacy consideration is that the privacy guarantees of partitioned cookies can be circumvented by browser extensions with host permissions.
 Extensions' background contexts can query and store cookies across partitions, meaning they could store a cross-site identifier across partitions.
-Unfortuately, this type of attack is unavoidable due to the nature of extensions.
+Unfortunately, this type of attack is unavoidable due to the nature of extensions.
 Even if we block partitioned cookies (or even all cookies) from extensions' background contexts, an extension could still use content scripts to write cross-site identifiers to the DOM which the site's own script could copy to the site's partitioned cookie jar.
 
 ## Alternate Designs for CHIPS