Update NOTES.md with another 2.4.4 change

Update NOTES.md

v2.4.2 release notes

Update release notes (rethinkdb#6909)

Fix CentOS8 and Stretch build in table_metadata.cc

Includes <math.h> header for ceil().

File modification notices (to appease Apache deities)

Fix Windows build

- Adjusts includes
- Fixes metadata_file_t namespacing/decl SNAFU
- Comment in WINDOWS.md

Regenerte web assets

Use --jobs=auto or -j7 with dpkg-buildpackage, depending on platform

Avoid browser-detection in JS driver

Makes the admin UI use a private API instead.  This way,
Electron clients can just use TcpConnection as the default.