I've tried to reconcile the commits in 0.21.3..master with the PR and Issue IDs in the change log. The following appear to be missing from doc/whats_new/v0.22.rst and entries should be added for them:
reconciled and found

• ENH faster polynomial features for dense matrices (Fixes #13173, implements faster polynomial features for dense matrices #13290)
• ENH Adds roc weighted scorers to SCORERS (ENH Adds roc weighted scorers to SCORERS #14417)
• ColumnTransformer input feature name and count validation (ColumnTransformer input feature name and count validation #14544)
• FEA Adds Plotting API to Partial Dependence ([MRG] Adds Plotting API to Partial Dependence #14646)
• Fix mixin inheritance order, allow overwriting tags (fix mixin inheritance order, allow overwriting tags #14884) (not sure if this needs an entry)
• EHN update lobpcg from scipy master (EHN update lobpcg from scipy master #14971)
• Error for cosine affinity when zero vectors present ([MRG] Error for cosine affinity when zero vectors present #7943)
• clone parameters issue with gridsearch etc: MRG clone parameters in gridsearch etc #15096