project: Update link to version.go now that it's in specs-go/
project: Update link to version.go now that it's in specs-go/

Catch up with 7bf06d5 (source and schema: differentiate with examples,
2015-12-18, #276).

Signed-off-by: W. Trevor King <f75897670c17327c42ab201733fb8a81ff9f4c34@tremily.us>

wking/opencontainer-runtime-spec,hqhq/specs,hqhq/runtime-spec,ujuc/specs,laijs/specs,vbatts/specs,wking/opencontainer-specs,opencontainers/runtime-spec,opencontainers/specs,jonboulle/specs,cloudfoundry-incubator/specs