Add documentation on endpoints options

[trevorhardy]

There are a number of endpoint options that are not documented in Configuration Options Reference and should be. Looking at the source code they appear to be:

• sourceOnly
• receiveOnly
• singleConnectionOnly
• multipleConnectionsAllowed
• connectionRequired
• connectionOptional

Some of these are identical to what is available in the value interfaces and can likely leverage that documentation. Restructuring of the documentation my be in order.