Merge branch 'master' into issue-467

Author: evanp

ERRATA.md

@@ -4,7 +4,7 @@ This document includes errata for the [Activity Streams](https://www.w3.org/TR/a
 
 ## Activity Streams
 
-- None yet reported.
+  - None yet reported.
 
 ## Activity Vocabulary
 
@@ -42,4 +42,23 @@ This document includes errata for the [Activity Streams](https://www.w3.org/TR/a
         }
       ]
     }
-    ```
+    ```
+    
+  - The range of the `units` property is given as an enumerated set of values.
+    Due to a formatting error, some of these values are shown with an incorrect
+    leading space character. The correct range is:
+    
+    ```text
+    "cm" | "feet" | "inches" | "km" | "m" | "miles" | xsd:anyURI
+    
+  - Example 58 includes a `summary` property on a `Mention` object, which is
+    not allowed. A corrected example:
+    
+    ```json
+    {
+      "@context": "https://www.w3.org/ns/activitystreams",
+      "type": "Mention",
+      "href": "http://example.org/joe",
+      "name": "Joe"
+    }
+    ```