Merge pull request #13061 from laurocaetano/fix-uniqueness-validation-for-aliased-attribute

Fix bug when validating the uniqueness of an aliased attribute.
Conflicts:
	activerecord/CHANGELOG.md
[ci skip] used new syntax for scopes
Merge pull request #13070 from kuldeepaggarwal/documentation-updation

[ci skip] used new syntax for scopes
[ci skip]removed obsolete information about `options` parameter in create method
Merge pull request #13071 from kuldeepaggarwal/documentation-updation

[ci skip]removed obsolete information about `options` parameter in create method