doc: copy readme from ariga/atlas repo #667

Job	Run time
Lint	3m 53s
Acceptance Tests (Terraform 1.5.*)	3m 55s
Build provider bundles	4m 21s
Acceptance Tests (Terraform 1.6.*)	3m 53s
Acceptance Tests (Terraform 1.7.*)	3m 58s
Integration SQLite (Terraform 1.5.*)	19s
Integration PostgreSQL (Terraform 1.5.*)	42s
Integration SQL Server (Terraform 1.5.*)	50s
Integration SQLite (Terraform 1.6.*)	20s
Integration MySQL (Terraform 1.5.*)	55s
Integration PostgreSQL (Terraform 1.6.*)	44s
Integration SQLite (Terraform 1.7.*)	22s
Integration SQL Server (Terraform 1.6.*)	54s
Integration MySQL (Terraform 1.6.*)	46s
Integration PostgreSQL (Terraform 1.7.*)	45s
Integration SQL Server (Terraform 1.7.*)	47s
Integration MySQL (Terraform 1.7.*)	47s
	28m 11s

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