Deprecate old modules

[vweevers]

Ref: How do I upgrade to abstract-level?

First let's do a doc-deprecation (too many downloads still):

• memdown
• level-mem
• abstract-leveldown
• level-js
• levelup
• leveldown
• deferred-leveldown
• encoding-down
• level-codec
• multileveldown
• level-party
• subleveldown
• level-errors
• level-packager
• level-concat-iterator
• rocksdb
• level-rocksdb

Then npm deprecation and archival of repo:

• memdown with message Superseded by memory-level (https://github.com/Level/community#faq)
• level-mem with message Superseded by memory-level (https://github.com/Level/community#faq)
• abstract-leveldown with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-js with message Superseded by browser-level (https://github.com/Level/community#faq)
• levelup with message Superseded by abstract-level (https://github.com/Level/community#faq)
• leveldown with message Superseded by classic-level (https://github.com/Level/community#faq)
• deferred-leveldown with message Superseded by abstract-level (https://github.com/Level/community#faq)
• encoding-down with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-codec with message Superseded by level-transcoder (https://github.com/Level/community#faq)
• multileveldown with message Superseded by many-level (https://github.com/Level/community#faq)
• level-party with message Superseded by rave-level (https://github.com/Level/community#faq)
• subleveldown with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-errors with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-packager with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-concat-iterator with message Superseded by abstract-level (https://github.com/Level/community#faq)
• level-test with message Discontinued
• rocksdb with message Discontinued (https://github.com/Level/community#faq)
• level-rocksdb with message Discontinued (https://github.com/Level/community#faq)