Add documentation for '--task--include-statistics' switch

Also move the task plugin example to the example section, since it feels
out of place between the documentation for switches.

Change-Id: I6f2d2c43dfb1a176ce45f970bf99b2b3fcd4e95e

src/main/java/com/googlesource/gerrit/plugins/task/Modules.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/Modules.java b/src/main/java/com/googlesource/gerrit/plugins/task/Modules.java
index f70a5dd..179d1e6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/Modules.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/Modules.java
@@ -87,7 +87,7 @@
     @Option(name = "--evaluation-time", usage = "Include elapsed evaluation time on each task")
     public boolean evaluationTime = false;
 
-    @Option(name = "--include-statistics", usage = "Include statistcs about the task evaluations")
+    @Option(name = "--include-statistics", usage = "Include statistics about the task evaluations")
     public boolean includeStatistics = false;
 
     @Option(name = "--summary-count", usage = "number of items to output in statistics summaries")

src/main/resources/Documentation/task.md

diff --git a/src/main/resources/Documentation/task.md b/src/main/resources/Documentation/task.md
index 931b3f9..b37f52a 100644
--- a/src/main/resources/Documentation/task.md
+++ b/src/main/resources/Documentation/task.md
@@ -636,6 +636,24 @@
 switch outputs an elapsed time value on every task indicating how much time
 it took to evaluate a task and its subtasks.
 
+**\-\-@PLUGIN@\-\-include-statistics**
+
+A debug switch to include statistics about internal task plugin properties.
+This is intended to help task configurators and system administrators profile
+task queries to help improve their performance. This option adds some task
+plugin statistics to each of the tasks and the overall query statistics to
+the last change in the query.
+
+**\-\-@PLUGIN@\-\-only**
+
+This switch can be used to only evaluate tasks under a certain root when tasks
+from other roots are unwanted. For example, a CI system may not be interested
+in evaluating tasks for another CI system. The switch can be provided multiple
+times.
+
+Examples
+--------
+
 When tasks are appended to changes, they will have a "task" section under
 the plugins section like below:
 
@@ -654,15 +672,6 @@
         status: PASS
 ```
 
-**\-\-@PLUGIN@\-\-only**
-
-This switch can be used to only evaluate tasks under a certain root when tasks
-from other roots are unwanted. For example, a CI system may not be interested
-in evaluating tasks for another CI system. The switch can be provided multiple
-times.
-
-Examples
---------
 See [task_states](test/task_states.html) for a comprehensive list of examples
 of task configs and their states.