Update HltEfficiencyChecker documentation for MooreAnalysis!17

Following !541 (merged), HltEfficiencyChecker now runs the HLT2 reconstruction by default (MooreAnalysis!17 (merged)). The documentation has been updated to reflect this. I also fixed a couple of typos.

Preview with Moore/run make -C Moore/doc html but the changes are pretty minimal.

I also added this tutorial to the CODEOWNERS list.

Given the changes are just to the docs, a passing pipeline should be all the testing this needs.

Needs MooreAnalysis!17 (merged) for the examples to work.

added Documentation label

mentioned in merge request MooreAnalysis!17 (merged)

assigned to @jonrob

approved this merge request

merged

mentioned in commit a23be6d8

unassigned @jonrob and @msaur

mentioned in issue #198 (closed)