docs: Add "Contributing" section to README

README.md

@@ -5,6 +5,7 @@
 * [What is StrataTrapper upscaling toolkit?](#what-is-stratatrapper-upscaling-toolkit)
 * [Code structure](#code-structure)
 * [How to run codes](#how-to-run-codes)
+* [Contributing](#contributing)
 * [References](#references)
 
 ## What is StrataTrapper upscaling toolkit?
@@ -38,6 +39,10 @@ Other folder and files are repository-related.
 5. Use `Result/ECLIPSE_RUN.DATA` as an input for reservoir simulation software.
   The generated file corresponds to the version 2019 of ECLIPSE.
 
+## Contributing
+
+Everyone is welcome to open [issues](https://github.com/ImperialCollegeLondon/StrataTrapper/issues) and [pull requests](https://github.com/ImperialCollegeLondon/StrataTrapper/pulls).
+
 ## References
 
 Please refer to the User Manual in the `Reference` folder