Add examples for framework agreements

[jpmckinney]

Making in a PR so that I can review.

[jpmckinney]

This might need significant changes, depending on how #440 is resolved (see latest comment there).

[yolile]

Some comments from discussions/retreat;

• It is preferable to always use a new process for each call off even if it is a direct call off without competition and then, for direct call offs:

  • Add an Award object to awards and a Contract object to contracts
  • Set awards.id and contracts.id to the same value
  • Populate the awards.value, awards.contractPeriod and awards.items fields with the initial contract value, period and items respectively
  • If the contract value, period or items are subsequently updated, populate the contracts.value, contracts.period and contracts.items fields with the updated value

• We need a field to distinguish the FA tender from the traditional ones: we can use the techniques extension https://github.com/open-contracting-extensions/ocds_techniques_extension

• We need a field to distinguish the mini competition tenders from the direct call offs: the direct call offs are going to be modeled as a new process without the tender block.

• FA duration: the duration is mappend in the tender.contractPeriod field

• To map all the buyers who participate in the FA dont map the buyer object but include multiples parties with 'buyer' role

• For indicate who buyer is buying what, as each call off is a new process, use the buyer object in that new process.

• As each mini competition or call of is a new process, use the planning block to indicate the budget for that purchase.

cc @jpmckinney

[jpmckinney]

@yolile: Can you work with @duncandewhurst next week to rewrite this page based on the discussion at the retreat?

[jpmckinney]

Closing this PR as I think the updates will be easier to review as a new PR.

I assume @yolile's notes from the retreat will all be reflected in the new PR. If not, please create/update an issue with any outstanding notes.