Update service discovery references

[ersonp]

Did you run make format && make check?

Fixes #

Changes:

• Change proxyDiscovery to serviceDiscovery

How to test this PR:

[jdknives]

Should we rename the package appdisc as well? Or is just responsible for updating app statuses in service discovery? Also do we need to define a config migration, right ? Also, please add changes to changelog. Will need to start doing that more diligently.

[ersonp]

• We can name appdisc to updatedisc instead since that is what it's doing since appdisc can be confusing.
• The updateUrls in parse takes care of the migration. Only thing is that the URL is changed to http://sd.skycoin.com with it.
• Will add all the changes of config v1.1.0 to Changelog. Also, I will need some inputs for all the changes introduced in the current version of skywire@develop.