I looking for a simple example of how to display a written transcript file for an item - just the code that can be added to the 'show.php' file.

You can add transcripts to the 'Transcription' item type field which is found when selecting Moving Image or Sound item types. Also the "text" field when selecting a Document type can be used as a transcription. You can always add the Transcription field to another item type's list of available field my editing the Item Type.

When you add the text into the Transcription/text field, the text will appear on the items/show.php page together with other item metadata. The transcript would then be searchable.

If you are interested in a document viewer, we are getting ready to release a new version within a week or so. This would create a viewer for any document file on the items/show.php page. The document's content would not be searchable via Omeka's search, but there is a search function for each document file.