chore: add contributing guideline

Author: antoine-coulon

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# Contributing to NodeSecure
+
+Contributions to NodeSecure include code, documentation, answering user questions and
+running the project's infrastructure
+
+The NodeSecure project welcomes all contributions from anyone willing to work in
+good faith with other contributors and the community. No contribution is too
+small and all contributions are valued.
+
+This guide explains the process for contributing to the NodeSecure project's.
+
+## [Code of Conduct](https://github.com/NodeSecure/Governance/blob/main/CODE_OF_CONDUCT.md)
+
+The NodeSecure project has a
+[Code of Conduct](https://github.com/NodeSecure/Governance/blob/main/CODE_OF_CONDUCT.md)
+that *all* contributors are expected to follow. This code describes the
+*minimum* behavior expectations for all contributors.
+
+See [details on our policy on Code of Conduct](https://github.com/NodeSecure/Governance/blob/main/COC_POLICY.md).
+
+<a id="developers-certificate-of-origin"></a>
+## Developer's Certificate of Origin 1.1
+
+By making a contribution to this project, I certify that:
+
+* (a) The contribution was created in whole or in part by me and I
+  have the right to submit it under the open source license
+  indicated in the file; or
+
+* (b) The contribution is based upon previous work that, to the best
+  of my knowledge, is covered under an appropriate open source
+  license and I have the right under that license to submit that
+  work with modifications, whether created in whole or in part
+  by me, under the same open source license (unless I am
+  permitted to submit under a different license), as indicated
+  in the file; or
+
+* (c) The contribution was provided directly to me by some other
+  person who certified (a), (b) or (c) and I have not modified
+  it.
+
+* (d) I understand and agree that this project and the contribution
+  are public and that a record of the contribution (including all
+  personal information I submit with it, including my sign-off) is
+  maintained indefinitely and may be redistributed consistent with
+  this project or the open source license(s) involved.