inline rollup glossary

What

Merge the local glossary from the Smart Rollups page <https://tezos.gitlab.io/alpha/smart_rollups.html#glossary> into the main glossary.

Why

As rollups gradually become mainstream, their terms deserve the same visibility as any other terms defined by the Tezos protocol.

How

Preliminary operations (in separate commits, to facilitate review):

• Fix the section structure of the page. Currently the Overview section spans the whole page (except only the Glossary).
• Fix somehow the conflict between the terms "Staker" in rollups (operator publishing commitments) and "Staker" in L1 (account staking to its delegator)
• Make the local glossary self-contained by adding definitions for some terms used but not defined, such as "Commitment".
• Add qualifiers for some terms to avoid clashes with identic terms in other domains (e.g. "Commitment" is also used in Timelock, Sapling, DAL, etc).

Once these are solved:

• the glossary can be merged in the global glossary, probably all going in section "Protocol terms".

Manually testing the MR

Checkout the additions to the global glossary.

Checklist

• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR