[framework] add README for the mirror repo (#15227)

aptos-move/framework/README-MIRROR-REPO.md

@@ -0,0 +1,24 @@
+# The Aptos Framework Repo
+
+This repository serves as a mirror for the Aptos Framework packages, including the Move standard library. The contents are synced from [aptos-core](https://github.com/aptos-labs/aptos-core) on an hourly basis.
+
+By pulling dependencies from this mirror repository, developers can avoid downloading unnecessary data, reducing build time significantly.
+
+## Usage
+To use the packages in this repository as dependencies in your Move project, you can include them in your move.toml file by adding them as Git dependencies.
+
+To add a dependency from this repository, include the following in your `move.toml` file:
+```
+[dependencies]
+<package_name> = { git = "https://github.com/aptos-labs/aptos-framework.git", subdir = "<path_to_directory_containing_Move.toml>", rev = "<commit_hash_or_branch_name>" }
+```
+For example, to add `AptosFramework` from the `mainnet` branch, you would use:
+```
+AptosFramework = { git = "https://github.com/aptos-labs/aptos-framework.git", subdir = "aptos-framework", rev = "mainnet" }
+```
+Make sure to replace `subdir` with the appropriate path if you are referencing a different package within the framework.
+
+## Contributing
+If you want to contribute to the development of the framework, please submit issues and pull requests to the [aptos-core](https://github.com/aptos-labs/aptos-core) repository, where active development happens.
+
+Bugs, feature requests, or discussions of enhancements will be tracked in the issue section there as well. This repository is a mirror, and issues will not be tracked here.