.arcconfig

narrow: mark wire proto capability names experimental and versioned

We already plan to add a "widen" wire protocol command to the "narrow"
capability, so let's version the capabilities as "exp-narrow-1" and
"exp-ellipses-1". When we add the "widen" command, we will then add a
"exp-narrow-2" capability to indicate support for that command.

Differential Revision: https://phab.mercurial-scm.org/D4529

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}