Merge pull request #25 from marian-nmt/romang/example-library-readme

Replace the marian-example-library submodule with README

Author: snukky

.gitmodules

@@ -0,0 +1,57 @@
+# Example: Marian as a library
+
+This serves as a minimal example of a CMake project with a [marian][marian]
+dependency. The dependency to Marian in that repository is facilitated by a
+submodule to [marian-dev]. The complete code is available from the
+[marian-example-library] repository.
+
+
+## Usage
+
+### Compile
+```shell
+git clone https://github.com/marian-nmt/marian-example-library
+cd marian-example-library
+mkdir build
+cd build
+cmake ..
+cmake --build .
+```
+
+### Run
+```shell
+./example
+```
+
+## About this example
+The code in [src/main.cpp](src/main.cpp) builds a simple expression graph using
+Marian. It mirrors the example found in Marian's [developer
+documentation][dev_docs].
+
+The expression graph represents `z = x*y + sin(x)`, with an absolute-error
+applied to `z` as a loss function. It performs a forward and backward
+evaluation of the graph, and a single update of the graph parameters from a
+`Stochastic Gradient Descent` optimizer. Following the example, `x` takes the
+place of a learnable parameter.
+
+After the parameter update, the graph parameters are saved to
+`example-model.npz`. You can inspect its contents with
+[`script/read-npz.py`](/script/read-npz.py).
+
+Please refer to the [marian][marian] project for further documentation.
+
+## About this repository
+There are example CI builds available for
+  - Ubuntu
+  - MacOS
+  - Windows
+
+These compile and run the example executable.
+
+Additionally, the Marian submodule is updatable via dependabot.
+
+<!-- Links -->
+[marian]: https://marian-nmt.github.io/
+[marian-dev]: https://github.com/marian-nmt/marian-dev
+[marian-example-library]: https://github.com/marian-nmt/marian-example-library
+[dev_docs]: https://marian-nmt.github.io/docs/api/graph.html