[HTML] Multi-line examples aren't displayed multi-line

Description

Multi-line example return data isn't displayed as multi-line.

Swagger-codegen version

2.2.1

Swagger declaration file content or url

---
swagger: '2.0'
info:
  version: 0.0.0
  title: Simple API
paths:
  /:
      responses:
        200:
          description: OK
          schema:
            type: string
            example: |
              foo
              bar

Expected Result:

"foo bar"

Result:

"foo\nbar\n"

Use the supplied Swagger 2.0 declaration as the reproduction case, focusing on the HTML output for the multi-line string example. Compare the expected and actual rendering, then verify that the generated result preserves the line break without the extra trailing newline; no source file or test is named in the issue.