Check Text fix text mismatch

[rx294]

https://github.com/mitre/stig-microsoft-iis-8.5-server-baseline/blob/aafcd00a9243f1912447bc69df8d0d64acaead26/controls/V-76687.rb#L116

Fix text direct with incomplete guidance adding:

 Click on the \"Source Type\" drop-down list and select \"Server Variable\".
  Click “OK” to add.

but check text does not ask to check for that field

and earlier version of the directs as below:

Click on the "Source Type" drop-down list and select "Server Variable".
Click on the "Source" drop-down list and select "HTTP_CONNECTION".
Click OK to add.

if Server Variable is to added the check must be modified as below to follow the same pattern as the rest

it { should match /sourceName\s+:\s+HTTP_CONNECTION\s+sourceType\s+:\s+ServerVariable/ }