added chapter 3 and refactor of chapter 1 and chapter 2

0x0001_hello-world/.vscode/extensions.json

@@ -1,10 +1,9 @@
 {
-    // See http://go.microsoft.com/fwlink/?LinkId=827846
-    // for the documentation about the extensions.json format
-    "recommendations": [
-        "platformio.platformio-ide"
-    ],
-    "unwantedRecommendations": [
-        "ms-vscode.cpptools-extension-pack"
-    ]
+  "recommendations": [
+    "marus25.cortex-debug",
+    "ms-vscode.cmake-tools",
+    "ms-vscode.cpptools",
+    "ms-vscode.cpptools-extension-pack",
+    "ms-vscode.vscode-serial-monitor"
+  ]
 }

0x0001_hello-world/.vscode/settings.json

@@ -1,5 +1,30 @@
 {
+    // These settings tweaks to the cmake plugin will ensure
+    // that you debug using cortex-debug instead of trying to launch
+    // a Pico binary on the host
+    "cmake.statusbar.advanced": {
+        "debug": {
+            "visibility": "hidden"
+        },
+        "launch": {
+            "visibility": "hidden"
+        },
+        "build": {
+            "visibility": "hidden"
+        },
+        "buildTarget": {
+            "visibility": "hidden"
+        }
+    },
+    "cmake.buildBeforeRun": true,
+    "cmake.configureOnOpen": true,
+    "cmake.configureSettings": {
+      "CMAKE_MODULE_PATH": "${env:PICO_INSTALL_PATH}/pico-sdk-tools"
+    },
+    "cmake.generator": "Ninja",
+    "C_Cpp.default.configurationProvider": "ms-vscode.cmake-tools",
+    "C_Cpp.errorSquiggles": "enabled",
     "files.associations": {
-        "stm32f4xx.h": "c"
+        "stdlib.h": "c"
     }
-}
+}