Add a Getting Started

Author: Antoine Riard

CONTRIBUTING.md

@@ -24,6 +24,26 @@ requests.
 Major projects are tracked [here](https://github.com/rust-bitcoin/rust-lightning/projects).
 Major milestones are tracked [here](https://github.com/rust-bitcoin/rust-lightning/milestones?direction=asc&sort=title&state=open).
 
+Getting Started
+---------------
+
+First and foremost, start small.
+
+This doesn't mean don't be ambitious with the breath and depth of your contributions but rather
+understand the project context and culture before to invest an asymmetric number of hours on
+development compare to your merged work.
+
+Even if you have an extensive open source background or sound software engineering skills, consider
+that technical correctness is as much important that its comprehensions by the other set of regular
+contributors.
+
+It's very welcome to ask for review, either on IRC or LDK. And also for reviewers, it's nice to
+provide timelines when you hope to fulfill the request. but bearing in mind for both side that's a
+"soft" commitment.
+
+If you're eager to fasten the dev process, reviewing other contributors work is the best you can do
+while waiting review on yours.
+
 Contribution Workflow
 ---------------------