feat: prepare DFTE 1.0.2

docs/GETTING_STARTED.md

@@ -0,0 +1,42 @@
+# Getting started
+
+DFTE renders a named root template through a `TemplateContext`. Register templates and placeholder values once, then ask the renderer for fixed-size chunks until completion.
+
+```cpp
+#include <Arduino.h>
+#include <TemplateEngine.h>
+
+static const char ROOT[] PROGMEM = R"DFTE(
+<h1>%TITLE%</h1><p>Uptime: %UPTIME%</p>
+)DFTE";
+
+PlaceholderRegistry registry;
+TemplateContext context;
+
+void setup() {
+    Serial.begin(115200);
+    registry.registerProgmemData(PSTR("%TITLE%"), PSTR("DFTE Quickstart"));
+    registry.registerRamData(PSTR("%UPTIME%"), []() -> const char* {
+        static char value[16];
+        snprintf(value, sizeof(value), "%lus", millis() / 1000);
+        return value;
+    });
+    registry.registerProgmemTemplate(PSTR("%ROOT%"), ROOT);
+    context.setRegistry(&registry);
+    TemplateRenderer::initializeContext(context, PSTR("%ROOT%"));
+}
+
+void loop() {
+    uint8_t chunk[128];
+    if (!TemplateRenderer::isComplete(context) && !TemplateRenderer::hasError(context)) {
+        const size_t written = TemplateRenderer::renderNextChunk(context, chunk, sizeof(chunk));
+        Serial.write(chunk, written);
+    }
+}
+```
+
+`registerProgmemData()` is for static flash data. `registerRamData()` takes a getter for a value that can change as chunks are rendered. `registerProgmemTemplate()` lets a placeholder expand to another template.
+
+For a buildable project, start with [HelloPlaceholder](../examples/HelloPlaceholder/). Next: [template language](TEMPLATE_LANGUAGE.md).
+
+Back to [documentation](README.md) · [project overview](../README.md).