docs: add progressive "Task Lists" sections to CONTRIBUTING.md (#22537)

Author: mid1221213

CONTRIBUTING.md

@@ -1,3 +1,43 @@
+## How to help and contribute to the V project
+
+The tasks in the lists below are ordered in terms of easiness/time/nerves
+investment.
+
+### Starting tasks
+
+1. Read the [language documentation](https://docs.vlang.io/introduction.html) and [standard module documentation](https://modules.vlang.io/).
+
+2. Fix doc errors and places you found unclear, and make [PRs](https://github.com/vlang/v/pulls) about it.
+
+3. Make V programs, in the areas that you are interested in, or help others make
+   V programs. If the programs/libraries are public, post them to the channel
+   `#showcase-discussion` on [Discord](https://discord.gg/vlang) and/or to
+   [awesome-v](https://github.com/vlang/awesome-v). You can also answer other
+   people's questions in Discord channels `#help` or `#v-chat`, or in
+   [github's discussions page](https://github.com/vlang/v/discussions).
+
+4. Read the new issues in the tracker.
+
+5. Try to reproduce them on your system, and comment in the issues, with the
+   results.
+
+6. Read the PRs, try to spot errors in them, and comment about them.
+
+### Medium tasks (after gathering experience with 1..6)
+
+7. Make PRs, with bug fixes to existing issues (found doing 1..6).
+
+8. Suggest new features, tools, or modifications to the existing ones here,
+   based on the experience, that you gathered doing 1..7.
+
+9. Make PRs with implementations of your suggestions, or based on other people's
+   suggestions, based on 1..7 and the feedback from 8.
+
+### Advanced tasks (after doing 1..9 for a while)
+
+10. Work on [V RFCs](https://github.com/vlang/rfcs/) (submitting new ones,
+    providing feedback to existing ones, implementing them).
+
 ## Code Structure
 
 I tried to make the code of the compiler and vlib as simple and readable as