Broken links in README.md

[edwardsph]

Just going through the Vocabularies list I found a few broken links:

1. Solid leader: https://github.com/solid/information/blob/master/solid-team.md#solid-leader
2. Pad: https://www.w3.org/ns/pim/pad#
3. Patch: https://www.w3.org/ns/pim/patch#

It's a useful list though!