Update the documentation description for "config-service.cache.enabled"

[klboke]

What's the purpose of this PR

The config-service.cache.enabled configuration adjustment requires a restart of configService to take effect, add this note

[codecov]

Codecov Report

Merging #4785 (7dbfa7b) into master (d1fb1ed) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4785      +/-   ##
============================================
- Coverage     47.26%   47.22%   -0.04%     
- Complexity     1657     1659       +2     
============================================
  Files           346      346              
  Lines         10683    10683              
  Branches       1063     1063              
============================================
- Hits           5049     5045       -4     
- Misses         5328     5331       +3     
- Partials        306      307       +1     

Impacted Files	Coverage Δ
...oServiceRegistryDeregisterApplicationListener.java	30.00% <0.00%> (-45.00%)	⬇️
...work/apollo/biz/message/ReleaseMessageScanner.java	82.89% <0.00%> (-2.64%)	⬇️
...ervice/service/ReleaseMessageServiceWithCache.java	87.05% <0.00%> (+1.17%)	⬆️
...mework/apollo/openapi/service/ConsumerService.java	58.46% <0.00%> (+1.53%)	⬆️
...nfigservice/service/AccessKeyServiceWithCache.java	84.69% <0.00%> (+2.04%)	⬆️
...framework/apollo/openapi/entity/ConsumerAudit.java	48.48% <0.00%> (+6.06%)	⬆️

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[nobodyiam]

LGTM