fix: add missing yaml tag for mtls spec config

[zcong1993]

Description

Add missing yaml tag for mtls spec config which might be used as sentry Self-hosted config. And this example in document https://docs.dapr.io/operations/security/mtls/#sentry-configuration-1 not works for now before fix.

Issue reference

Please reference the issue this PR will close: #[issue number]

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Unit tests passing
• End-to-end tests passing
• Extended the documentation / Created issue in the https://github.com/dapr/docs/ repo: dapr/docs#[issue number]
• Specification has been updated / Created issue in the https://github.com/dapr/docs/ repo: dapr/docs#[issue number]
• Provided sample for the feature / Created issue in the https://github.com/dapr/docs/ repo: dapr/docs#[issue number]

[codecov]

Codecov Report

Merging #3864 (841ba9f) into master (c78a815) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3864   +/-   ##
=======================================
  Coverage   62.46%   62.46%           
=======================================
  Files         101      101           
  Lines        9525     9525           
=======================================
  Hits         5950     5950           
  Misses       3109     3109           
  Partials      466      466           

Impacted Files	Coverage Δ
pkg/config/configuration.go	71.01% <ø> (ø)

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[mukundansundar]

lgtm