use sync.Once instead

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

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.

Write the PID file after listening.

The new version of bitswap should improve server-side ("seeding") performance
with high-latency disks.

ipfs namespace is now being provided to prometheus

feat: web ui 2.5.8

docs: add connmgr to config.md toc

feat: web ui 2.5.7

fix(pin): wait till after fetching to remove direct pin

Otherwise, we could abort while fetching the graph and stay in a state where the
direct pin is removed.

fixes #4650

Relevant release notes can be found on [v2.5.5](https://github.com/ipfs-shipyard/ipfs-webui/releases/tag/v2.5.5).

README: improve build documentation

fixes #6704