Change semmantical analyzis to tree validation as per @matklad

Co-Authored-By: Aleksey Kladov <aleksey.kladov@gmail.com>

crates/ra_syntax/src/syntax_error.rs

@@ -5,7 +5,7 @@
 use crate::{TextRange, TextUnit};
 
 /// Represents the result of unsuccessful tokenization, parsing
-/// or semmantical analyzis.
+/// or tree validation.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct SyntaxError(String, TextRange);