Remove all mentions of mdbook-mermaid, which is no longer used

.github/workflows/ci.yml

@@ -9,17 +9,16 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v5
 
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: nightly
           components: rust-docs
 
-      - uses: jontze/action-mdbook@v2
+      - uses: jontze/action-mdbook@v4
         with:
           token: ${{secrets.GITHUB_TOKEN}}
-          use-mermaid: true
 
       - name: Check for broken links
         run: |
@@ -38,7 +37,7 @@ jobs:
 
       - name: Deploy
         if: ${{ github.event_name == 'workflow_dispatch' || (github.event_name == 'push' && github.ref == 'refs/heads/main') }}
-        uses: appleboy/scp-action@v0.1.7
+        uses: appleboy/scp-action@v1
         with:
           host: docs.espressif.com
           username: ${{ secrets.PRODUCTION_USERNAME }}

README.md

@@ -4,13 +4,13 @@ This repository contains the source of "The Rust on ESP" book.
 
 ## Quickstart
 
-This book is generated using [`mdbook`] and additionally uses the [`mdbook-mermaid`] preprocessor to add support for diagrams. To install these tools:
+This book is generated using [`mdbook`], which can be installed using Cargo:
 
 ```shell
-cargo install mdbook mdbook-mermaid
+cargo install mdbook
 ```
 
-With `mdbook` and `mdbook-mermaid` installed, you can clone the repository and start a development server by running:
+With `mdbook` installed, you can clone the repository and start a development server by running:
 
 ```shell
 git clone https://github.com/esp-rs/book
@@ -19,7 +19,6 @@ mdbook serve
 ```
 
 [`mdbook`]: https://github.com/rust-lang/mdBook
-[`mdbook-mermaid`]: https://github.com/badboy/mdbook-mermaid
 
 ## License