Fix a comment in the generated config

[richvdh]

Changing macaroon_secret_key no longer logs you out (as of #4374)

[codecov-io]

Codecov Report

Merging #4387 into develop will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #4387      +/-   ##
===========================================
- Coverage    73.67%   73.65%   -0.02%     
===========================================
  Files          300      300              
  Lines        29815    29815              
  Branches      4897     4897              
===========================================
- Hits         21965    21961       -4     
- Misses        6408     6412       +4     
  Partials      1442     1442

Impacted Files	Coverage Δ
synapse/config/key.py	67.64% <ø> (ø)	⬆️
synapse/storage/background_updates.py	93% <0%> (-2.8%)	⬇️
synapse/handlers/user_directory.py	71.08% <0%> (-0.31%)	⬇️
synapse/util/file_consumer.py	82.45% <0%> (+1.75%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7e41545...ca87ce8. Read the comment docs.