### Motivation

Replace all ```global zookeeper``` with  ```configuration store``` in all documents.

Relates to #3338
Closes #3305 

## Motivation
Fix #3119. This allows to configure region-aware policy and read-reordering so that brokers first read on bookies of their own region.

## Modifications
1. Added parameters:
```
// Enable region-aware bookie selection policy. BK will chose bookies from
// different regions and racks when forming a new bookie ensemble
// If enabled, the value of bookkeeperClientRackawarePolicyEnabled is ignored
bookkeeperClientRegionawarePolicyEnabled=false

// Enable/disable reordering read sequence on reading entries.
bookkeeperClientReorderReadSequenceEnabled=false
```

2. Fixed bug in ZkBookieRackAffinityMapping: the value set to racksWithHost by deserialize() was overriden by the affectation in setConf(). The fix just moves the hostname workaround in setConf().

## Result
Users can enable bookkeeperClientRegionawarePolicyEnabled and bookkeeperClientReorderReadSequenceEnabled to make brokers read on bookies of their own region

* PIP-25: Token based authentication

* Addressed comments

* Use Authorization header

* Update to support env: data: and file: as sources for keys and tokens

* Fixed cli description

* Updated broker.conf

* Improved consistency in reading keys and CLI tools

* Fixed check for http headers

* Accept rel time with no specified unit

* Fixed reading data: URL

* Addressed comments

* Added integration tests

* Addressed comments

* Added CLI command to validate token against key

* Fixed integration tests

* Removed env:

* Fixed rel time parsing

PR #1225 added the ability to configure the TLS protocol version and
cipher on the server side, but this was never added to the
documentation. This patch fixes that omission.

Issue: #2402

* Removed mentions to incubator-pulsar

* Removed DISCLAIMER link from offloaders package

* Trigger build

### Motivation

Increasing the default value of `maxConcurrentLookupRequests` from 10K to 50K to increase limit of sustainable lookups before rejecting requests.

### Motivation

The default timeout for broker graceful shutdown is set to 3 seconds. This can give little room to do graceful shutdown when the broker is serving a lot of topics.

There is no big downside in increasing the timeout to a much bigger value.

### Changes

Break down the `Concepts and Architecture` page into multiple pages and move it as a separate top-level category.

### Motivation

Improve the documentation and usability of the pulsar website. This moves the website and documentation to a new framework (https://docusaurus.io/)  which will make it easier to maintain going forward.

### Modifications

A new version of the website in site2 directory. Also updates the pulsar build docker to add the new website build dependencies.

### Result

A more usable website and documentation.

A preview of the site can be seen here: https://cckellogg.github.io/incubator-pulsar
*All the links and images might not work on this site since it's a test only site*