Revise meetup page

Summary:
Revise according to recent change.

Also revise .arcconfig as linter codes are deleted from this branch. Otherwise "arc" always fails. This branch is supposed to contain rocksdb.org webpages, no RocksDB source codes. So no linter is fine.

Test Plan: N/A

Reviewers: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17187