docker-login: add page (#6137)

pages/common/docker-login.md

@@ -0,0 +1,20 @@
+# docker login
+
+> Log into a docker registry.
+> More information: <https://docs.docker.com/engine/reference/commandline/login/>.
+
+- Interactively log into a registry:
+
+`docker login`
+
+- Log into a registry with a specific username (user will be prompted for a password):
+
+`docker login --username {{username}}`
+
+- Log into a registry with username and password:
+
+`docker login --username {{username}} --password {{password}} {{server}}`
+
+- Log into a registry with password from stdin:
+
+` echo "{{password}}" | docker login --username {{username}} --password-stdin`