Fix a missing preposition in plugin doc
In "While there are no hard and fast rules for the structure a plugin"
a preposition is missing between "structure" and "a plugin", this is
to fix it.
Change-Id: Ib22f614dece35d2ed79fa660027e50840e77d7bb
diff --git a/doc/source/plugin.rst b/doc/source/plugin.rst
index 2afb1e5..6f6621d 100644
--- a/doc/source/plugin.rst
+++ b/doc/source/plugin.rst
@@ -132,7 +132,7 @@
Plugin Structure
================
-While there are no hard and fast rules for the structure a plugin, there are
+While there are no hard and fast rules for the structure of a plugin, there are
basically no constraints on what the plugin looks like as long as the 2 steps
above are done. However, there are some recommended patterns to follow to make
it easy for people to contribute and work with your plugin. For example, if you