Change normative language in Microsyntax non-normative section

ERRATA.md

@@ -80,3 +80,5 @@ This document includes errata for the [Activity Streams](https://www.w3.org/TR/a
   - Unlike `latitude` and `longitude`, the domain of the `altitude` term is the `Object` type. The `altitude` term should be included in the list of properties of an `Object`. Because `altitude` is primarily documented as a property of a `Place`, publishers should not include `altitude` on objects that are not of type `Place`, and consumers should accept objects with this property that aren't of type `Place`.
 
   - The domain of the `attributedTo` property is both `Link` and `Object`. `attributedTo` should be included in the list of properties of a `Link`.
+
+  - The second paragraph in the non-normative section "Mentions, Tags and Other Common Social Microsyntaxes" should read, 'While such microsyntaxes can be used within the values of the `content`, `name`, and `summary` properties on an Activity Streams Object, implementations are not required to parse the values of those properties in order to determine the appropriate routing of notifications, categorization, or linking between objects. Instead, publishers make appropriate use of the vocabulary terms provided specifically for these purposes.'