docs: Fix typo in header routing specification docs

[mjallday]

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional with a list of types and scopes found here, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I've signed my commits with DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
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• My organization is added to USERS.md.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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[github-actions]

Go Published Test Results

1 983 tests   1 983 ✔️  2m 37s ⏱️
   118 suites         0 💤
       1 files           0 ❌

Results for commit 584f4a1.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e8d1117) 81.68% compared to head (584f4a1) 81.68%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2808   +/-   ##
=======================================
  Coverage   81.68%   81.68%           
=======================================
  Files         133      133           
  Lines       20178    20178           
=======================================
  Hits        16483    16483           
  Misses       2843     2843           
  Partials      852      852           

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[github-actions]

E2E Tests Published Test Results

    4 files      4 suites   3h 28m 45s ⏱️
  96 tests   80 ✔️   5 💤 11 ❌
400 runs  364 ✔️ 20 💤 16 ❌

For more details on these failures, see this check.

Results for commit 584f4a1.