Fix references to outdated projects

[matkuliak]

Summary of the changes / Why this is an improvement

• Fixed outdated references
• Bumped build.json version to 2.1.2

Checklist

• Link to issue this PR refers to (if applicable): https://github.com/crate/tech-writing/issues/416
• CLA is signed

[matkuliak]

Complaint here: https://github.com/crate/cratedb-guide/actions/runs/8512692441/job/23314821079?pr=65#step:4:1232
It's "unsafe" but works, so not sure what to do with it.

[amotl]

Thanks!

[amotl]

Problem

x.509 certificates expired on https://tldp.org/.

(admin/going-into-production: line 365) broken https://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/index.html - HTTPSConnectionPool(host='tldp.org', port=443): Max retries exceeded with url: /LDP/Linux-Filesystem-Hierarchy/html/index.html (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1006)')))

-- https://github.com/crate/cratedb-guide/actions/runs/8512692441/job/23314821079?pr=65#step:4:1232

Advice

If this keeps going on, you will need to add the URL to the link checker ignores in conf.py. Thanks!

[matkuliak]

If this keeps going on, you will need to add the URL to the link checker ignores in conf.py. Thanks!

Right, will try couple more times and add it, if it persists. Thank you.