spec: change discovery path walking logic
spec: change discovery path walking logic

Rather than specifying that the path should be walked up on !(200, 3xx),
instead define it in terms of whether a 4xx code is encountered.

Also fixes minor formatting issue.

alban/appc-spec,appc/spec,dustymabe/spec,3ofcoins/appc-spec,dgonyeo/spec,alban/appc-spec,ChengTiesheng/spec,tklauser/spec,endocode/appc-spec,apcera/appc-spec,stufflebear/spec,craimbert/spec,tklauser/spec,3ofcoins/appc-spec,yifan-gu/spec,jonboulle/spec,dustymabe/spec,squeed/spec,ChengTiesheng/spec,squeed/spec,dgonyeo/spec,zenlinTechnofreak/spec,craimbert/spec,iaguis/appc-spec,ChengTiesheng/spec,tklauser/spec,marineam/spec,craimbert/spec,dgonyeo/spec,appc/spec,zenlinTechnofreak/spec,krnowak/appc-spec,iaguis/appc-spec,iaguis/appc-spec,squeed/spec,dustymabe/spec,yifan-gu/spec,alban/appc-spec,marineam/spec,stufflebear/spec,jonboulle/spec,jonboulle/spec,apcera/appc-spec,endocode/appc-spec,3ofcoins/appc-spec,endocode/appc-spec,appc/spec,yifan-gu/spec,marineam/spec,krnowak/appc-spec,krnowak/appc-spec,apcera/appc-spec,zenlinTechnofreak/spec,stufflebear/spec