Fix documentation for `{{ page.excerpt }}` (#6779)

Merge pull request 6779

docs/_docs/posts.md

@@ -207,7 +207,8 @@ filter by tags or any other variable created with extensions.
 ## Post excerpts
 
 Each post automatically takes the first block of text, from the beginning of
-the content to the first occurrence of `excerpt_separator`, and sets it as the `post.excerpt`.
+the content to the first occurrence of `excerpt_separator`, and sets it in the
+post's data hash.
 Take the above example of an index of posts. Perhaps you want to include
 a little hint about the post's content by adding the first paragraph of each of
 your posts:

docs/_docs/variables.md

@@ -250,7 +250,7 @@ following is a reference of the available data.
       <td><p><code>page.excerpt</code></p></td>
       <td><p>
 
-        The un-rendered excerpt of the Page.
+        The un-rendered excerpt of a document.
 
       </p></td>
     </tr>