`v2.0.0-beta.1` release preparation

[alejandro-vaz]

alpha development has concluded. the most significant changes to this first beta are:

• the allocator API
• modularization, except iterators
• reworked TaggedLen
• try_with_capacity
• reworked equality implementations
• into_raw_parts

subsequent beta releases will polish the codebase and its implementations to ensure stability, and simplify code. feature development has primarily ended

release checklist

• verify documentation builds
• bump version
• create tag and release with changelog
• publish

note: this release is scheduled for the 20th

special thanks to @fereidani, @bolshoytoster, @TDecking, @charliermarsh and @pedrodesu for making this possible

must get ready

#614

[alejandro-vaz]

#614 didn't get ready but it's okay, it will for the next beta. it's just a tiny doc change

[pedrodesu]

I can have the PR to that by tomorrow if you're interested.

[alejandro-vaz]

I already implemented it in #626

tomorrow I'll open more issues, no worries, I'll try to keep around ~20-30 recently open issues at any time