Update site to reflect dual branches (MystenLabs#3556)

* Update site to reflect dual branches

* Update index.md

* Update index.md

* Update install.md

* Update index.md

* Update index.md

* Update index.md

* Update install.md

* Update index.md

* Finish edits

* Update index.md

doc/src/build/install.md

@@ -2,10 +2,7 @@
 title: Install Sui
 ---
 
-Welcome to the Sui development environment! Note, this site is built from the upstream `main`
-branch and therefore will contain updates not yet found in `devnet`. The instructions here
-recommend use of `devnet` as the latest stable release. To [contribute to Sui](../contribute/index.md),
-instead use the `main` branch.
+Welcome to the Sui development environment! This site is available in two versions in the menu at top left: the default and stable [Devnet](https://docs.sui.io/devnet/learn) branch and the [Latest build](https://docs.sui.io/learn) upstream `main` branch. Use the `devnet` version for app development on top of Sui. Use the Latest build `main` branch for [contributing to the Sui blockchain](../contribute/index.md) itself. Always check and submit fixes to the `main` branch.
 
 ## Summary
 

doc/src/contribute/index.md

@@ -4,6 +4,8 @@ title: Contributing to Sui
 
 This page describes how to add to Sui. If you merely need to get the Sui binaries, follow [Install Sui](../build/install.md).
 
+This site is available in two versions in the menu at top left: the default and stable [Devnet](https://docs.sui.io/devnet/learn) branch and the [Latest build](https://docs.sui.io/learn) upstream `main` branch. Use the `devnet` version for app development on top of Sui. Use the Latest build `main` branch for contributing to the Sui blockchain as described on this page. Always check and submit fixes to the `main` branch.
+
 Find answers to common questions in our [FAQ](../contribute/faq.md). Read other sub-pages in this section for ways to contribute to Sui.
 
 ## See our roadmap
@@ -36,9 +38,7 @@ Select the **Sui Doc Bug** template, adjust fields, and describe the issue.
 
 ### Updates
 
-You may also make changes to the docs directly in GitHub right here using the **Source Code** link below.
-
-> **Important:** Make sure you are in the `main` rather than `devnet` branch in the URL.
+You may also make changes to the docs directly in GitHub right here using the **Source Code** link below. Make sure you are in the `main` rather than `devnet` branch by being on the [Latest build](https://docs.sui.io/learn) upstream view as described at the top of this page.
 
 Simply edit the file in question and generate a pull request. You may even use our [Sui doc templates](https://github.com/MystenLabs/sui/tree/main/doc/template) to create overviews and procedures (uses).
 
@@ -49,9 +49,6 @@ Then send your work our way. We will get back to you shortly.
 In order to obtain the Sui source code, follow the steps to download (`git clone`) the `sui` repository
 at [Install Sui](../build/install.md#source-code).
 
-> **Tip:** The install docs recommend use of the `devnet` branch as the last stable release. To instead
-> contribute changes to Sui, use the `main` branch.
-
 And see the Rust [Crates](https://doc.rust-lang.org/rust-by-example/crates.html) in use at:
 * https://mystenlabs.github.io/sui/ - the Sui blockchain
 * https://mystenlabs.github.io/narwhal/ - the Narwhal and Tusk consensus engine

doc/src/learn/index.md

@@ -10,12 +10,15 @@ programming language, you should familiarize yourself with it and use this conte
 
 For a deep dive into Sui technology, see the [Sui Smart Contracts Platform](https://github.com/MystenLabs/sui/blob/main/doc/paper/sui.pdf) white paper. Find answers to common questions about our [roadmap](https://github.com/MystenLabs/sui/blob/main/ROADMAP.md) and more in our [FAQ](../contribute/faq.md).
 
-> **Important:** This site is built from the upstream `main` branch and therefore will contain updates not yet found in `devnet`.
+> **Important:** This site is available in two versions in the menu at top left: the default and stable [Devnet](https://docs.sui.io/devnet/learn) branch and the [Latest build](https://docs.sui.io/learn) upstream `main` branch. Use the `devnet` version for app development on top of Sui. Use the Latest build `main` branch for [contributing to the Sui blockchain](../contribute/index.md) itself. Always check and submit fixes to the `main` branch.
+
+built from the upstream `main` branch and therefore will contain updates not yet found in `devnet`.
 
 ## See what's new
 
 Find the latest updates to these contents in this section:
 
+* This site is now available in two versions in the menu at top left: the default and stable [Devnet](https://docs.sui.io/devnet/learn) branch and the [Latest build](https://docs.sui.io/learn) upstream `main` branch. Use the `devnet` version for app development on top of Sui. Use the Latest build `main` branch for  [contributing to the Sui blockchain](../contribute/index.md) itself. Always check and submit fixes to the `main` branch.
 * Sui now supports development using [Microsoft Windows 11, macOS, and Linux](../build/install.md#supported-oses). See [install Sui](../build/install.md#prerequisites) for the prerequisites of each operating system.
 * `sui::id` is now `sui::object` and `VersionedID` is now `Info`. Use the [Object module](https://github.com/MystenLabs/sui/blob/main/crates/sui-framework/sources/object.move) that has [replaced the former ID.move.](https://github.com/MystenLabs/sui/pull/3241)
 * Find a list of [single-writer apps](../learn/single-writer-apps.md) that would benefit from Sui's advantages in handling [simple transactions](../learn/how-sui-works.md#simple-transactions).