DVC: add page including sub-commands checkout, init, add

pages/common/dvc-checkout.md

@@ -0,0 +1,16 @@
+# dvc checkout
+
+> Update data files and directories in the workspace based on current DVC-files.
+> More information: <https://dvc.org/doc/command-reference/checkout>.
+
+- Checkout to latest version, for all target files and directories:
+
+`dvc checkout`
+
+- Checkout to latest version, for a given target:
+
+`dvc checkout {{target}}`
+
+- Checkout specific version of target from different Git commit/tag/branch:
+
+`git checkout {{commit_hash/tag/branch}} {{target}} && dvc checkout {{target}}`