Document the correct default value of SOMAXCONN

Motivation:

Recently we changed the default value of SOMAXCONN that is used when we can not determine it by reading /proc/sys/net/core/somaxconn. While doing this we missed to update the javadocs to reflect the new default value that is used.

Modifications:

List correct default value in the javadocs of SOMAXCONN.

Result:

Correct javadocs.