chore: 更新 .gitignore 文件

- 添加 docs 文件夹到忽略列表，以忽略 Doxygen 生成的文件
- 保持原有的忽略规则不变

src/ccompiler/frontend/parser/ast.h

@@ -84,10 +84,10 @@ typedef struct ast_node {
     union {
         void *children[6];
         struct {
-            vector_header(children, struct ast_node *);
+            VECTOR_HEADER(children, struct ast_node *);
         } root;
         struct {
-            vector_header(children, struct ast_node *);
+            VECTOR_HEADER(children, struct ast_node *);
         } block;
         struct {
             symtab_key_t key;
@@ -95,7 +95,7 @@ typedef struct ast_node {
             tok_t tok;
         } syms;
         struct {
-            vector_header(params, struct ast_node *);
+            VECTOR_HEADER(params, struct ast_node *);
         } params;
         struct {
             struct ast_node * name;