Move from gitbook to docusaurus, build docs in Travis CI (#10970)

* fix: ignore unknown fields in more RPC responses

* Remove mdbook infrastructure

* Delete gitattributes and other theme related items

Move all docs to /docs folder to support Docusaurus

* all docs need to be moved to /docs

* can be changed in the future

Add Docusaurus infrastructure

* initialize docusaurus repo

Remove trailing whitespace, add support for eslint

Change Docusaurus configuration to support `src`

* No need to rename the folder! Change a setting and we're all good to
go.

* Fixing rebase items

* Remove unneccessary markdown file, fix type

* Some fonts are hard to read. Others, not so much. Rubik, you've been
sidelined. Roboto, into the limelight!

* As much as we all love tutorials, I think we all can navigate around a
markdown file. Say goodbye, `mdx.md`.

* Setup deployment infrastructure

* Move docs job from buildkite to travic

* Fix travis config

* Add vercel token to travis config

* Only deploy docs after merge

* Docker rust env

* Revert "Docker rust env"

This reverts commit f84bc208e807aab1c0d97c7588bbfada1fedfa7c.

* Build CLI usage from docker

* Pacify shellcheck

* Run job on PR and new commits for publication

* Update README

* Fix svg image building

* shellcheck

Co-authored-by: Michael Vines <mvines@gmail.com>
Co-authored-by: Ryan Shea <rmshea@users.noreply.github.com>
Co-authored-by: publish-docs.sh <maintainers@solana.com>

docs/src/implemented-proposals/commitment.md

@@ -1,4 +1,6 @@
-# Commitment
+---
+title: Commitment
+---
 
 The commitment metric aims to give clients a measure of the network confirmation
 and stake levels on a particular block. Clients can then use this information to
@@ -47,9 +49,10 @@ banks are not included in the commitment calculations here.
 
 Now we can naturally augment the above computation to also build a
 `BlockCommitment` array for every bank `b` by:
-1) Adding a `ForkCommitmentCache` to collect the `BlockCommitment` structs
-2) Replacing `f` with `f'` such that the above computation also builds this
-`BlockCommitment` for every bank `b`.
+
+1. Adding a `ForkCommitmentCache` to collect the `BlockCommitment` structs
+2. Replacing `f` with `f'` such that the above computation also builds this
+   `BlockCommitment` for every bank `b`.
 
 We will proceed with the details of 2) as 1) is trivial.
 
@@ -75,6 +78,7 @@ Now more specifically, we augment the above computation to:
 ```
 
 where `f'` is defined as:
+
 ```text
     fn f`(
         stake: &mut Stake,