Rewrite intro of how to use guide

* Mention that code owner approvals are required for submit.
* Add links to user guide.
* Drop information about who maintains the plugin as this is not
  relevant to users.
* Reformat the information about replacing the find-owners plugin as a
  note.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Id595ab0933eecafd57e7530b010c06849ad13a40
diff --git a/resources/Documentation/how-to-use.md b/resources/Documentation/how-to-use.md
index 0323f11..a052c4c 100644
--- a/resources/Documentation/how-to-use.md
+++ b/resources/Documentation/how-to-use.md
@@ -1,18 +1,20 @@
 # Intro
 
-The `code-owners` plugin provides support for code owners in Gerrit and is
-replacing the `find-owners` plugin.
+The `@PLUGIN@` plugin provides support for
+[code owners](user-guide.html#codeOwners) in Gerrit.
 
-For projects that used code owners with the `find-owners` plugin before, the
-existing `OWNERS` files continue to work and the only major difference is that
-the `code-owners` plugin comes with a new UI for selecting code owners and
-showing the code owner status.
+If the `@PLUGIN@` plugin is enabled, changes can only be submitted if all
+touched files are covered by [approvals](user-guide.html#codeOwnerApproval) from
+code owners.
 
-The `code-owners` plugin is an open-source plugin and is maintained by the
-Gerrit team at Google.
+**NOTE:** The `@PLUGIN@` is replacing the `find-owners` plugin. For projects that
+used code owners with the `find-owners` plugin before, the existing `OWNERS`
+files continue to work and the only major difference is that the `@PLUGIN@`
+plugin comes with a new UI for selecting code owners and showing the code owner
+status.
 
 This document focuses on the workflows in the UI. Further information can be
-found in the [backend user guide](user-guide.html).
+found in the [user guide](user-guide.html).
 
 ### Enable the plugin