This adds a detailed dashboard for tahoe-lafs running on one node.

Monitoring: Add regular scraping for Tahoe OpenMetrics statistics

Closes privatestorageops#285

See merge request !216

Update privatestorage.

See merge request !208

Update nixpkgs.

See merge request !214

add a rst version of our design template

See merge request !213

Fix https alerting

See merge request !210

Monitor MegaRAID on our storage nodes

Closes privatestorageops#19

See merge request !202

This is based on the version in google docs.
It has some changes informed by our experience using the template so far.

Update ops docs: No need for manually creating TLS keys for the payment server anymore

See merge request !212

Thanks @tomprince!

Thanks to @tomprince for the suggestion.

Since !146 (merged on 2021-09-07) we let the NixOS Let's Encrypt integration
with NGINX handle TLS.  That integration cares for interim self-signed certs
until real ones are aquired.  The section about creating TLS certs by hand so
the service will start is obsolote.

words about recovering from backup

Closes privatestorageops#276

See merge request !206

Don't literalExample all the examples

See merge request !209

Copy everything from how the issuer does it.

literalExample is deprecated and overused. See:
https://whetstone.privatestorage.io/privatestorage/PrivateStorageio/-/merge_requests/201#note_16966

Monitor TLS cert expiry

Closes privatestorageops#363

See merge request !201

Thanks for the suggestion @jcalderone!

As per our discussion in PrivateStorage sync meeting today.

This is a follow-up to !166 (c9ddc8ad), where I missed one occurence.

Update nixpkgs.

See merge request !207