Correct typo in documentation

corrected homonym error.
Improve ol.Collection documentation
Add @api to ol.Sphere
Merge pull request #2652 from fredj/collection-doc

Improve ol.Collection documentation
Add @classdesc to ol.Sphere
Make tissot example use ol.Sphere
Remove @api annotation from ol.sphere.WGS84
Merge pull request #2641 from elemoine/sphere

Add @api to ol.Sphere
New domain in the build header
Merge pull request #2660 from elemoine/domain

New domain in the build header
Merge pull request #2447 from lazaruslarue/patch-1

Correct documentation typo.
Delegate transformation to `ol.format.*`

Fixes #2604.
Merge pull request #2662 from gingerik/delegate-transformation

Delegate transformation in ol.source.FormatVector#readFeatures to `ol.format.*`
ol.layer.Vector.getSource return type specialisation.
Remove unnecessary type cast