[FAB-10657] Fix typos in logging-control.rst
[FAB-10657] Fix typos in logging-control.rst

Fix typo in docs/source/logging-control.rst:
  "subcommmand" to "subcommand"
  "varaibles" to "variables"

Change-Id: I5d1cf18ca802501da968e1b2f47312a5c0289c9a
Signed-off-by: Daisuke IIZUKA <ed453e9146c57858b1f982120fd18191f8583c64@hitachi.com>

hyperledger/fabric,manish-sethi/fabric-sidedb,stemlending/fabric,xixuejia/fabric,manish-sethi/fabric,muralisrini/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,jimthematrix/fabric,binhn/fabric,manish-sethi/fabric,stemlending/fabric,muralisrini/fabric,stemlending/fabric,muralisrini/fabric,jimthematrix/fabric,xixuejia/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,hyperledger/fabric,binhn/fabric,stemlending/fabric,binhn/fabric,manish-sethi/fabric-sidedb,xixuejia/fabric,manish-sethi/fabric-sidedb