Add liscence and prepare for OSS release

scripts/render_readme.py

@@ -6,9 +6,9 @@ Directive format (in README.md.in):
   <!-- @snippet path/to/file.cpp snippet_name -->
 
 Snippet tags (in C++ source files):
-  // [snippet: snippet_name]
+  // --8<-- [start:snippet_name]
   ...content...
-  // [/snippet: snippet_name]
+  // --8<-- [end:snippet_name]
 
 In Python files use # instead of //.
 """
@@ -33,8 +33,8 @@ def comment_prefix(path: Path) -> str:
 
 def extract_snippet(file_path: Path, name: str) -> str:
     prefix = comment_prefix(file_path)
-    open_tag  = f'{prefix} [snippet: {name}]'
-    close_tag = f'{prefix} [/snippet: {name}]'
+    open_tag  = f'{prefix} --8<-- [start:{name}]'
+    close_tag = f'{prefix} --8<-- [end:{name}]'
 
     text = file_path.read_text()
     lines = text.splitlines()