docs: add upgrading doc

CONTRIBUTING.md

@@ -107,18 +107,16 @@ Adminterface hosts release candidate builds on Github packages. If you wish to t
    ```
 
 ### Upgrading
-1. Replace the version of `adminterface` inside `Gemfile`
+1. Replace `$VERSION` with the target RC version.
    ```ruby
    source "https://rubygems.pkg.github.com/cmdbrew" do
-     # Replace [VERSION] with the target RC version
-     gem "adminterface", [VERSION]
+     gem "adminterface", "$VERSION"
    end
    ```
 2. Run `bundle install`
-3. Replace the version of `adminterface` inside `package.json`
+3. Replace `$VERSION` with the target RC version, and run:
    ```bash
-   # Replace [VERSION] with the target RC version
-   yarn upgrade @cmdbrew/adminterface@[VERSION]
+   yarn upgrade @cmdbrew/adminterface@$VERSION
    ```
 
 ## Releasing (maintainers only)

website/docs/start/cli.mdx

@@ -1,5 +1,5 @@
 ---
-sidebar_position: 2
+sidebar_position: 3
 description: Adminterface Command Line Reference.
 ---
 

website/docs/start/dependencies.mdx

@@ -1,5 +1,5 @@
 ---
-sidebar_position: 99
+sidebar_position: 98
 description: Adminterface Dependencies and Licenses.
 ---
 

website/docs/start/upgrading.mdx

@@ -0,0 +1,23 @@
+---
+sidebar_position: 2
+description: Adminterface Upgrading Guide.
+---
+
+# Upgrading
+We kept the NPM package and the Ruby gem versions in sync. When upgrading, please ensure you update them both.
+
+## Update the Gem
+Replace `$VERSION` with the target version.
+```ruby title="Gemfile"
+gem "adminterface", "$VERSION"
+```
+And, run:
+```bash
+bundle install
+```
+
+## Update the NPM package
+Replace `$VERSION` with the target version, and run:
+```bash
+yarn upgrade @cmdbrew/adminterface@$VERSION
+```