docs: migrate ABOUT-CI and ABOUT-NIGHTLY to dev docs site

Replace relative file links with absolute URLs and add centered page
headers
to the migrated docs. Update the dev sidebar to include the new pages.

4 files changed, 14 insertions, 6 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e8e4bed..ffb0064 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -70,7 +70,7 @@ After editing documentation, refresh relevant files:
 These steps are included in `cargo ci`; running `cargo ci` will execute them automatically.
 
 > [!TIP]
-> You can check the [ABOUT CI](./ABOUT-CI.md) section to learn how "Mingling CI" works.
+> You can check the [ABOUT CI](https://mingling-rs.github.io/mingling/docs/dev/#/pages/abouts/ci) section to learn how "Mingling CI" works.
 
 ## 4. Regarding AI Agent Usage
 
diff --git a/docs/dev/_sidebar.md b/docs/dev/_sidebar.md
index 5182676..e303735 100644
--- a/docs/dev/_sidebar.md
+++ b/docs/dev/_sidebar.md
@@ -5,6 +5,8 @@
   * [Some Situations Where You'd Be Like "Shit!"](pages/issues/the-shit-time)
 * 💡 Abouts
   * [AI Translation Rule](pages/abouts/ai-translation-rule)
+  * [About Mingling CI Process](pages/abouts/ci)
   * [Markdown Code Verification System](pages/abouts/code-verify-system)
+  * [About Nightly Features](pages/abouts/nightly-features)
 * 📄 Templates
   * [Helpdoc Template](pages/templates/doc)
diff --git a/ABOUT-CI.md b/docs/dev/pages/abouts/ci.md
index 4cbcd6f..3a93c1c 100644
--- a/ABOUT-CI.md
+++ b/docs/dev/pages/abouts/ci.md
@@ -1,4 +1,7 @@
-# About Mingling CI Process
+<h1 align="center">About Mingling CI Process</h1>
+<p align="center">
+    CI workflow and local execution guide for Mingling
+</p>
 
 Mingling's CI process is built into the project, with its execution logic located in `.run/src/bin/ci.rs`. You can run it locally via the `cargo ci` command, which produces the same results as the `CI` workflow in GitHub Actions.
 
@@ -12,13 +15,13 @@ An alias is defined in `.cargo/config.toml` at the project root:
 [alias]
 ci = "run --manifest-path .run/Cargo.toml --bin ci --quiet --"
 ```
-
+ 
 Simply execute:
 
 ```bash
 cargo ci
 ```
-
+ 
 ## CI Execution Flow
 
 `cargo ci` runs the following stages in order:
diff --git a/ABOUT-NIGHTLY.md b/docs/dev/pages/abouts/nightly-features.md
index f2d4ec7..13b666e 100644
--- a/ABOUT-NIGHTLY.md
+++ b/docs/dev/pages/abouts/nightly-features.md
@@ -1,4 +1,7 @@
-# About Nightly Rust
+<h1 align="center">About Nightly Features</h1>
+<p align="center">
+    Using nightly Rust features in Mingling
+</p>
 
 **Mingling** uses some features that are only available in the `nightly` toolchain. This requires you to enable the `nightly` feature:
 
@@ -6,7 +9,7 @@
 [dependencies]
 mingling = { version = "...", features = ["nightly"] }
 ```
-
+ 
 ## Features
 
 > [!WARNING]