Dated README links

[GinnyGlider]

Seven of the README links have become dated,
yet they still function due to redirects.
Two of the links are HTTP.
And One being a 404.
—
Here are the following lines of the dated links and their
new replacements (Based on the link's redirect destination) :
[Note: Due to GitHub's formatting, the order is new vs old links]
—
Redirects to: https://datatracker.ietf.org/doc/html/rfc7932

brotli/README.md

Line 15 in a47d747

The specification of the Brotli Compressed Data Format is defined in [RFC 7932](https://tools.ietf.org/html/rfc7932).

Redirects to: https://bazel.build/ (With HTTPS)

brotli/README.md

Line 40 in a47d747

See [Bazel](http://www.bazel.build/)

Redirects to: https://groups.google.com/g/brotli

brotli/README.md

Line 68 in a47d747

[brotli mailing list](https://groups.google.com/forum/#!forum/brotli).

Redirects to: HTTPS

brotli/README.md

Line 79 in a47d747

* [Large Text Compression Benchmark](http://mattmahoney.net/dc/text.html)

Redirects to: https://github.com/foliojs/brotli.js (Legal advice may be needed)

brotli/README.md

Line 87 in a47d747

JavaScript port of brotli [decoder](https://github.com/devongovett/brotli.js). Could be used directly via `npm install brotli`

Redirects to: 404 (Legal advice may be needed)

brotli/README.md

Line 93 in a47d747

Dart [native bindings](https://github.com/thosakwe/brotli)

Redirects to: https://pub.dev/documentation/es_compression/latest/brotli/

brotli/README.md

Line 95 in a47d747

Dart compression framework with [fast FFI-based Brotli implementation](https://pub.dev/documentation/es_compression/latest/brotli/brotli-library.html) with ready-to-use prebuilt binaries for Win/Linux/Mac

—
Reasoning behind this issue:
I have come over from nixpkgs repository after a pull-request concerning
an outdated Internet-Draft link which lead to a 404. In order to update it
I had to find an official source, which was the Brotli repository itself.
—
The new link source I choose here was https://tools.ietf.org/html/rfc7932
However, despite being official it leads as a redirect, so I opted to instead
update it with the redirect destination, which (at the time of writing) is:
https://datatracker.ietf.org/doc/html/rfc7932
—
I needed the nix Brotli package but the description and the dated
Internet-Draft link ignored me enough to create a PR there and
an issue here. I decided to briefly examine the README page
for dated links, and here I am with this issue. I'm sure there
are others here too, but that's what I have the time for.
—
It's a minor issue, I know I could've done a PR, however the
requirement for sighing a CLA is about as far as I can pursue
for a simple change.