Rename book-example to guide (#1336)

`book-example` is a bit of a strange name given that it's not just an
example.

Author: camelid

.github/workflows/deploy.yml

@@ -31,12 +31,12 @@ jobs:
     - name: Install Rust (rustup)
       run: rustup update stable --no-self-update && rustup default stable
     - name: Build book
-      run: cargo run -- build book-example
+      run: cargo run -- build guide
     - name: Deploy to GitHub
       env:
         GITHUB_DEPLOY_KEY: ${{ secrets.GITHUB_DEPLOY_KEY }}
       run: |
-        touch book-example/book/.nojekyll
+        touch guide/book/.nojekyll
         curl -LsSf https://raw.githubusercontent.com/rust-lang/simpleinfra/master/setup-deploy-keys/src/deploy.rs | rustc - -o /tmp/deploy
-        cd book-example/book
+        cd guide/book
         /tmp/deploy

.gitignore

@@ -4,7 +4,7 @@ target
 .DS_Store
 
 book-test
-book-example/book
+guide/book
 
 .vscode
 tests/dummy_book/book/

Cargo.toml

@@ -8,7 +8,7 @@ authors = [
 ]
 documentation = "http://rust-lang.github.io/mdBook/index.html"
 edition = "2018"
-exclude = ["/book-example/*"]
+exclude = ["/guide/*"]
 keywords = ["book", "gitbook", "rustbook", "markdown"]
 license = "MPL-2.0"
 readme = "README.md"