Please perform the following gis.stackexchange.com retagging actions:
This means that in the future, even when there will be an OpenLayers with major version 4,5,6,..., all OpenLayers questions should be tagged openlayers.
Currently, gis.stackexchange.com has the tags openlayers, openlayers-2 and openlayers-3. "OpenLayers 3" has been rebranded to simply "OpenLayers", to make it easier to switch to semantic versioning in the future.
When OpenLayers 2 was still more widely used than OpenLayers 3, openlayers-2 was introduced. Both openlayers and openlayers-2 have since been used for OpenLayers 2 questions, but were never made synonyms.