BUG-731: rename LSPID and SRPID

This adds a bit of documentation and renames the offending generic
arguments to L (for LSP) and S (for SRP).

Change-Id: I2854f2cbc5df345b4febcebc229f7ec22ae5c7fc
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-731: rename LSPID and SRPID"