feat: add documentation macro system header

Adds C++ preprocessor macros for consistent API documentation.
Addresses issue #92.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/McRFPy_Doc.h

@@ -0,0 +1,31 @@
+#ifndef MCRFPY_DOC_H
+#define MCRFPY_DOC_H
+
+// Section builders for documentation
+#define MCRF_SIG(params, ret) params " -> " ret "\n\n"
+#define MCRF_DESC(text) text "\n\n"
+#define MCRF_ARGS_START "Args:\n"
+#define MCRF_ARG(name, desc) "    " name ": " desc "\n"
+#define MCRF_RETURNS(text) "\nReturns:\n    " text "\n"
+#define MCRF_RAISES(exc, desc) "\nRaises:\n    " exc ": " desc "\n"
+#define MCRF_NOTE(text) "\nNote:\n    " text "\n"
+
+// Link to external documentation
+// Format: MCRF_LINK("docs/file.md", "Link Text")
+// Parsers detect this pattern and format per output type
+#define MCRF_LINK(ref, text) "\nSee also: " text " (" ref ")\n"
+
+// Main documentation macros
+#define MCRF_METHOD_DOC(name, sig, desc, ...) \
+    name sig desc __VA_ARGS__
+
+#define MCRF_FUNCTION(name, ...) \
+    MCRF_METHOD_DOC(#name, __VA_ARGS__)
+
+#define MCRF_METHOD(cls, name, ...) \
+    MCRF_METHOD_DOC(#name, __VA_ARGS__)
+
+#define MCRF_PROPERTY(name, desc) \
+    desc
+
+#endif // MCRFPY_DOC_H