Expand readme and grammar notes

Author: theodorejb

README.md

@@ -2,6 +2,9 @@
 
 Parse [Handlebars](https://handlebarsjs.com) templates to a spec-compliant AST with PHP.
 
+Implements the same lexical analysis and grammar specification as Handlebars.js, so any template
+which can (or cannot) be parsed by Handlebars.js should parse (or error) the same way here.
+
 ## Installation
 
 `composer require devtheorem/php-handlebars-parser`
@@ -21,6 +24,16 @@ $result = $parser->parse($template);
 If the template contains invalid syntax, an exception will be thrown.
 Otherwise, `$result` will contain a `DevTheorem\HandlebarsParser\Ast\Program` instance.
 
+## Whitespace handling
+
+The parser can be created with an optional boolean argument,
+to support the `ignoreStandalone` Handlebars compilation option:
+
+```php
+$parser = (new ParserFactory())->create(ignoreStandalone: true);
+```
+
 ## Author
 
-Theodore Brown
+Theodore Brown  
+https://theodorejb.me

grammar/handlebars.y

@@ -37,9 +37,10 @@
 %%
 
 /*
- * Should match the grammar (as of 2025-01-20) of
- * https://github.com/handlebars-lang/handlebars-parser/blob/master/src/handlebars.yy
- * EBNF grammar has been converted to BNF.
+ * Grammar should match https://github.com/handlebars-lang/handlebars-parser/blob/master/src/handlebars.yy
+ * as of 2026-02-20. EBNF grammar has been converted to BNF.
+ * Exception: the hash and array literal syntax (https://github.com/handlebars-lang/handlebars-parser/pull/15)
+ * has been reverted for parity with the released version of Handlebars.js.
  */
 
 program: