Organizer images must be jpeg

Author: bridgetkromhout

REFERENCE.md

@@ -127,7 +127,7 @@ Each team member is an element of `team_members`.
 | `facebook` | String | No       | The full URL to the person's Facebook page                                                                                                                 | "https://www.facebook.com/sally.fields"                                                                                                                                                                                                                                                                             |
 | `linkedin` | String | No       | The full URL to the person's LinkedIn page                                                                                                                 | "https://www.linkedin.com/in/sallyfields"                                                                                                                                                                                                                                                                           |
 | `website`  | String | No       | The full URL to the person's webpage                                                                                                                       | "https://mattstratton.com"                                                                                                                                                                                                                                                                                          |
-| `image`    | String | No       | The name of the image for this user, located in `static/events/YYYY-CITY/organizers/`. This image must be either 300px square or (optimally) 600px square. | "sally-fields.jpg"                                                                                                                                                                                                                                                                                                  |
+| `image`    | String | No       | The name of the image for this user, located in `static/events/YYYY-CITY/organizers/`. This image must be a JPEG, either 300px square or (optimally) 600px square. | "sally-fields.jpg"                                                                                                                                                                                                                                                                                                  |
 | `bio`      | String | No       | The bio for the user. Markdown is supported. Quotation marks must be escaped.                                                                              | "Thought leader paradigm affordances physical computing quantitative vs. qualitative disrupt thought leader disrupt. Venture capital Steve Jobs pitch deck moleskine sticky note agile Steve Jobs pivot disrupt grok driven. Human-centered design bootstrapping agile driven grok food-truck ship it long shadow." |
 
 #### Organizer Emails