Added contributing instructions

Author: pavelgj

CONTRIBUTING.md

@@ -0,0 +1,90 @@
+# Contributing to Genkit
+
+## Build it
+
+```
+npm i
+npm run build:all
+```
+
+This will build all packages in this repository. This is recommended the first time you check out a fresh repo or pull new revisions.
+
+## Pack it
+
+Pack packages for testing/distribution.
+
+Assuming you built everything previously....
+
+```
+npm run pack:all
+```
+
+this will produce tarballs in the `dist` folder. Also `genkit-dist.zip` -- a zip of all the package tarballs.
+
+## Link it
+
+You will need the genkit CLI to run samples and the Dev UI
+
+```
+cd  genkit-tools
+npm link
+```
+
+## Run it
+
+In the `genkit/samples` folder you will find some samples. They might contain instructions for how to run them and what setup is necessary.
+
+Here's one that requires no setup:
+
+```
+cd genkit/samples/flows-sample1
+genkit flow:run basic "\"hello\""
+```
+
+Run the DevUI
+
+```
+cd genkit/samples/flows-sample1
+genkit start
+```
+
+Point your browser to http://localhost:4000
+
+## Code it
+
+FYI: `genkit` and `genkit-tools` are in two separate workspaces.
+
+As you make changes you may want to build an test things by running samples.
+You can reduce the scope of what you're building b
+
+```
+npm run build:genkit 
+npm run build:genkit-tools
+```
+
+But you can also go into specific package that you changed and run
+
+```
+npm run build
+```
+
+If you are going to be coding for a while they do
+
+```
+npm run build:watch
+```
+
+in the package that you're editing.
+
+## Send it
+
+Once done coding you will want to send a PR. Always do things in a separate branch (by convention name the branch `your_name-feature-something`).
+
+Before sending the PR alwaya run
+
+```
+npm run format
+npm run build:all
+```
+
+