sdkmanager: add page (#4077)

pages/common/sdkmanager.md

@@ -0,0 +1,20 @@
+# sdkmanager
+
+> Tool to install packages for the Android SDK.
+> More information: <https://developer.android.com/studio/command-line/sdkmanager>.
+
+- List available packages:
+
+`sdkmanager --list`
+
+- Install a package:
+
+`sdkmanager {{package}}`
+
+- Update every installed package:
+
+`sdkmanager --update`
+
+- Uninstall a package:
+
+`sdkmanager --uninstall {{package}}`