Update event reference response content description

[timkimadobe]

Description

Updates the Edge response content event description in event reference docs in line with Android docs:
adobe/aepsdk-edge-android#85

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #386 (b183bf1) into dev (0ebc5e7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #386   +/-   ##
=======================================
  Coverage   96.77%   96.77%           
=======================================
  Files          27       27           
  Lines        1671     1671           
=======================================
  Hits         1617     1617           
  Misses         54       54