DOC Fix references to missing examples
fix incorrect reference
Merge pull request #1986 from jaquesgrobler/DOC_reference_fixes

Doc reference fixes
TST Use assert_almost_equal in test_symmetry
COSMIT prefer partial over lambda in test_metrics
TSTFIX use name, not metric, in test_metrics error messages

Also, fix error messages without spaces
DOC correct note on handling 0-denominator in P/R/F