I'm renaming the PivotSchemaChanges.md into SchemaSwap.md, modifying it to
describe the current schema swap process and reformatting to be easier to read
in an editor.
I'm also modifying the replication docs to mention schema swap instead of pivot,
and to correct a few not quite factually correct statements.
The site needed publishing after #2312 and maybe after some other changes.
On the way I fixed a couple of incorrect things in vtctl docs (typo in an error
message and change of tablet type name WORKER->DRAINED that happened in #2151).
We'll switch serving vitess.io:
- before: from the gh-pages branch
- now: from the docs directory out of the master branch
This way it is much easier to update the website:
- no switching between branches required
- no untracked files get in our way in the gh-pages branch
- generated pages can be written in place and do not have to be moved around
- website can be updated and published in the same pull request