improve documentation and fix dht put bug

Adding alias for `ipfs repo stat`.

doc(gateway): document dnslink

pin: add context and error return to most of the Pinner functions

fix issue 6760, adding with hash-only, high CPU usage.

use sync.Once instead

This add -H (-h is obviously taken by the help) for human and -s for size only (I though of -so but multiple letters is automaticaly -- not -).

chore(dep): update QUIC

This is a large protocol breaking change. That's why QUIC is experimental.

fix go-lint

feat: web ui 2.7.1

fix(coreapi/add): close the fake repo used when adding with hash-only

fix bug 6748

ipfs add whit only hash, don't need to announce cid to other peer

Stdin can't have newlines, command-line arguments can't include null characters,
DHT values can include both.

This is a breaking change but this API has never worked anyways.

fixes #5112

fixes #6749

fixes #6744

doc(README): document requirements for cross-compiling with OpenSSL support

feat: web ui 2.6.0

See https://github.com/ipfs-shipyard/ipfs-webui/releases/tag/v2.6.0.

Add high-level go-ipfs architecture diagram

fixes #6736

docs: remove extra ) on the example README

update maintainer label

The `MAINTAINER` Dockerfile instruction has been deprecated, and the [dockerfile documentation](https://docs.docker.com/engine/reference/builder/#maintainer-deprecated) recommends using `LABEL maintainer="..."`. This commit updates the Dockerfile to use the recommended form.

dep: update bitswap for improved performance

Just make sure we've removed all the blocks. We can't guarantee that the size
will revert.