[Xorp-hackers] Cli style guide draft

[Pavlin Radoslavov]

Now that we've reached an aggreement, I've added the new rules to
the cli-style document.

Also, now that we started adding policy rules for modifying the CLI
commands, I added one more rule (originally suggested by Hasso some
time ago in a Bugzilla comment):

* If a command is changed (renamed, deleted or moved), the original
  command should be marked as "deprecated" (i.e., by using the
  "%deprecated" keyword in the rtrmgr template) and kept in the
  configuration tree for at least three major releases or 18 months
  (whichever comes later).

  For example, if a command is deprecated in Release-1.5, the deprecated
  state about that command can be removed in Release-1.8 (assuming there
  have been at least 18 months between those two releases).


The particular details about this rule can be modified as
appropriate.

Pavlin