Update CONTRIBUTING.md

Added Dennis Hall

Author: andyjohnson

CONTRIBUTING.md

@@ -54,6 +54,7 @@
 | David Ells         | Rustici Software |
 | David N. Johnson   | Clear Learning Systems |
 | David Pate         | Riptide Software |
+| Dennis Hall        | Learning Templates
 | Doug Hagy          | Twin Lakes Consulting Corporation |
 | Eric Johnson       | Planning and Learning Technologies, Inc. |
 | Fiona Leteney      | Feenix e-learning |
@@ -383,4 +384,4 @@ Hashes (#) should be used for all headings following the following format:
 ### 1.1 Top level property (3 hashes)
 #### 1.1.1 next level (4 hashes)
 ##### 1.1.1.1 next level and any deeper levels (5 hashes)
-###### Rationale, details etc. (6 hashes)
+###### Rationale, details etc. (6 hashes)