adds my primary contributions, other edits to membership table

[tvanepps]

Following recent discussion on github and elsewhere, the membership agreed to add an "eligible contributions" column to the membership table. Main rationale being that this info is more useful than org affiliation (to both members and the broader Ethereum community): it better describes what types of contributions the mechanism targets. It also reaffirms Protocol Guild's emphasis on individuals and their relevant work as being independent of the funding/hosting org.

This PR:

1. adds a link to the repo most closely relevant to my contributions in this markdown link format:[protocolguild/documentation] (https://github.com/protocolguild/documentation)
2. Deletes my org affiliation
3. renames the "Eligible Work" column to "Primary Contributions"

Members should do the same, choosing whichever example below fits best. There will likely be edge cases, but none that we can't figure out.

• Github: [org/repo] (github.com/org/repo)
• ethresearch: [ethresear.ch/u/username] (ethresear.ch/u/username)
• HackMD: [hackmd.io/@username] (hackmd.io/@username)

In the future we may also consider making it even more granular than a single link/repo, and require periodic refreshes (e.g. 3 link references from the past 3-6 months of work)

[kamilchodola]

@tvanepps out of curiosity as it caused some confusion now in our team - leaving an empty cell (which originally was a team assignment) is done by purpose? Everyone followed that but not sure why we keep this single cell empty instead of simply removing it?