[doc] Improve the dev install doc (taichi-dev#3685)

* [doc] Improve the dev install doc

* Update CONTRIBUTING.md

Co-authored-by: Vissidarte-Herman <[email protected]>

* tweaks

* tweaks

* Update CONTRIBUTING.md

Co-authored-by: Vissidarte-Herman <[email protected]>

* Update README.md

Co-authored-by: Vissidarte-Herman <[email protected]>

* Auto Format

* Update CONTRIBUTING.md

Co-authored-by: Vissidarte-Herman <[email protected]>
Co-authored-by: Taichi Gardener <[email protected]>

CONTRIBUTING.md

@@ -1,3 +1,7 @@
 # Contributing Guide
 
-See the [Contribution Guidelines](https://docs.taichi.graphics/lang/articles/contribution/contributor_guide) on our documentation site.
+Thank you for your interest in contributing to Taichi! Please check out the [Contribution Guidelines](https://docs.taichi.graphics/lang/articles/contribution/contributor_guide) for how to make a contribution.
+
+## Developer Installation
+
+Taichi is developed mainly in C++17 and Python3. Please check out the [Developer Installation](https://docs.taichi.graphics/lang/articles/contribution/dev_install) to build Taichi from source. Note that Taichi is LLVM-10.0.0 dependent and that we recommend installing [our pre-built LLVM libraries](https://docs.taichi.graphics/lang/articles/contribution/dev_install#installing-dependencies) for your platform.

README.md

@@ -47,9 +47,9 @@ Please build from source for other configurations (e.g., your CPU is ARM, or you
  - On Windows, please install [Microsoft Visual C++ Redistributable](https://aka.ms/vs/16/release/vc_redist.x64.exe) if you haven't.
  - [[All releases]](https://github.com/taichi-dev/taichi/releases)
 
-## Developer Installation
+## Contributing
 
-Please follow [this doc](https://docs.taichi.graphics/lang/articles/contribution/dev_install) to learn how to build Taichi from source. Note that Taichi requires LLVM-10.0.0, and it is recommneded to use [our prebuilt LLVM libraries](https://docs.taichi.graphics/lang/articles/contribution/dev_install#installing-dependencies) for each platform.
+We'd love to hear your comments or any of your feedback! If you would like to contribute to Taichi, please check out the [Contribution Guidelines](CONTRIBUTING.md) first.
 
 ## Contributors
 
@@ -59,8 +59,6 @@ Please follow [this doc](https://docs.taichi.graphics/lang/articles/contribution
 
 -------------------------------
 
-We welcome feedback and comments. If you would like to contribute to Taichi, please check out our [Contributor Guidelines](https://docs.taichi.graphics/lang/articles/contribution/contributor_guide).
-
 If you use Taichi in your research, please cite related papers:
 
 - [**(SIGGRAPH Asia 2019) Taichi: High-Performance Computation on Sparse Data Structures**](https://yuanming.taichi.graphics/publication/2019-taichi/taichi-lang.pdf) [[Video]](https://youtu.be/wKw8LMF3Djo) [[BibTex]](https://raw.githubusercontent.com/taichi-dev/taichi/master/misc/taichi_bibtex.txt) [[Code]](https://github.com/taichi-dev/taichi)

docs/lang/articles/contribution/dev_install.md

@@ -425,7 +425,7 @@ The `develop` command serves the developers' needs better because edits to the P
 
 ## Troubleshooting and debugging
 
-### `llvm-as` cannot be opened
+### `llvm-as` cannot be opened on macOS
 
 **Description**
 
@@ -462,7 +462,7 @@ You did not use the `--recursive` flag when cloning the Taichi repository.
 
 **Workaround**
 
-Run `git submodule update --init --re``cursive --depth=1`.
+Run `git submodule update --init --recursive --depth=1`.
 
 ### `which python` still returns the system's Python location