Add pre-reqs and tasks for launching a live version of the docs site

.devcontainer/Dockerfile

@@ -0,0 +1,11 @@
+FROM mcr.microsoft.com/devcontainers/rust:1-1-bullseye
+
+USER vscode
+
+# Install nightly toolchain to give access to nightly features for docs-site build.
+RUN rustup toolchain install nightly
+
+# Install pre-requisite tools
+RUN cargo install \
+    cargo-watch \
+    http-server

.devcontainer/devcontainer.json

@@ -2,7 +2,9 @@
 // README at: https://github.com/devcontainers/templates/tree/main/src/rust
 {
   "name": "Azure SDK for Rust",
-  "image": "mcr.microsoft.com/devcontainers/rust:1-1-bullseye",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
   "onCreateCommand": ".devcontainer/oncreate",
   "features": {
     "ghcr.io/devcontainers/features/azure-cli:1": {},
@@ -20,4 +22,4 @@
       ]
     }
   }
-}
+}

.vscode/cspell.json

@@ -6,11 +6,13 @@
     "**/test-resources.bicep",
     "**/test-resources.json",
     ".devcontainer/devcontainer.json",
+    ".devcontainer/Dockerfile",
     ".devcontainer/oncreate",
     ".github/CODEOWNERS",
     ".github/dependabot.yml",
     ".vscode/cspell.json",
     ".vscode/extensions.json",
+    ".vscode/tasks.json",
     "NOTICE.txt",
     "eng/",
     "*.dict.txt",

.vscode/tasks.json

@@ -0,0 +1,22 @@
+{
+  "tasks": [
+    {
+      "label": "Start docs site (requires nightly)",
+      "options": {
+        "cwd": "${workspaceFolder}"
+      },
+      "command": "cargo",
+      "args": [
+        "watch",
+        "-s",
+        "RUSTDOCFLAGS=\"--cfg=docsrs --enable-index-page -Z unstable-options\" cargo +nightly doc --all-features --workspace --no-deps",
+        "-s",
+        "http-server --index --port 8080 ./target/doc"
+      ],
+      "isBackground": true,
+      "problemMatcher": [
+        "$rustc"
+      ]
+    }
+  ]
+}