Documentation: Fix configuration description

[StMarian]

What this PR does / why we need it:
Fix configuration doc

Which issue(s) this PR fixes:
none

Special notes for your reviewer:

Checklist

• Documentation added
• Tests updated

[CLAassistant]

All committers have signed the CLA.

[codecov-io]

Codecov Report

Merging #3373 (0a305a7) into master (287244d) will increase coverage by 0.46%.
The diff coverage is 66.54%.

@@            Coverage Diff             @@
##           master    #3373      +/-   ##
==========================================
+ Coverage   62.44%   62.91%   +0.46%     
==========================================
  Files         200      205       +5     
  Lines       17101    17396     +295     
==========================================
+ Hits        10679    10944     +265     
- Misses       5457     5469      +12     
- Partials      965      983      +18     

Impacted Files	Coverage Δ
cmd/docker-driver/main.go	0.00% <0.00%> (ø)
cmd/migrate/main.go	5.40% <0.00%> (ø)
cmd/querytee/main.go	0.00% <0.00%> (ø)
pkg/chunkenc/memchunk.go	68.10% <0.00%> (ø)
pkg/distributor/http.go	0.00% <0.00%> (ø)
pkg/ingester/stream.go	70.86% <0.00%> (ø)
pkg/ingester/tailer.go	43.80% <0.00%> (ø)
pkg/logcli/client/client.go	5.50% <0.00%> (-0.06%)	⬇️
pkg/logcli/query/query.go	34.80% <0.00%> (ø)
pkg/logcli/query/tail.go	0.00% <0.00%> (ø)
... and 73 more

[slim-bean]

LGTM Thanks!