docs: fix observability README docs link

[NicholasBlaskey]

Ticket

Description

Test Plan

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

[netlify]

✅ Deploy Preview for determined-ui canceled.

Name	Link
🔨 Latest commit	4ca6a15
🔍 Latest deploy log	https://app.netlify.com/sites/determined-ui/deploys/6658ac1db08fec00085c5771

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.57%. Comparing base (ca60325) to head (4ca6a15).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9453      +/-   ##
==========================================
- Coverage   48.57%   48.57%   -0.01%     
==========================================
  Files        1233     1233              
  Lines      159168   159168              
  Branches     2777     2778       +1     
==========================================
- Hits        77316    77315       -1     
- Misses      81678    81679       +1     
  Partials      174      174              

Flag	Coverage Δ
backend	42.14% <ø> (-0.01%)	⬇️
harness	64.08% <ø> (ø)
web	44.29% <ø> (ø)

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see 7 files with indirect coverage changes