Address some of JC's review comments
Expand the 'End-to-End Signing' section
Update README.rst
Update README.rst
Remove informal language in the 'Snapshot Process' section and add a JC request
Merge branch 'master' of https://github.com/vladimir-v-diaz/pep-maximum-security-model
Update README.rst

Fix typographical error in previous commit: "timesetamp"
Merge branch 'master' of https://github.com/theupdateframework/pep-maximum-security-model
Remove mention of the bins role, fix formatting of some text, and use 'digest.filename'
Reorganize the 'Consistent Snapshots' and 'Auditing Snapshots' sections
Clarify that the 'digest.filename' convention is recommended
Roles signed by offline keys have been bolded in Table 1
Remove bolded unclaimed role, reference to a consistent snapshot process, and developer-provided threshold value from transactions
Expand the 'Automated Signing Solution' section
Expand the key management section and summarize its subsections
Fix reference link to RSA
Do not say that queues MAY be processed serially (we do not want offline roles to block others)
Fix introductory paragraph in the 'In the Event of a Key Compromise' section
Format role names
In 'Rationale', only mention the reason for extending PEP 458.

Do not mention the decision to integrate TUF with PyPI in two phases: it only led to confusion.
Move the easy-to-use key management solution and the central build farm paragraphs to other sections.
Minor edits to text.