Placeholder for examples/custom_search_comamnds/README.md

Soft link from examples/custom_search_commands to splunklib/searchcommands is a convenience for development that will be soon be replaced by a build step and/or install script.

Signed-off-by: David Noble <dnoble@splunk.com>
Fixed broken misplaced link

Signed-off-by: David Noble <dnoble@splunk.com>