docs: add file.abs and file.exists documents

docs/reference/model/file.md

@@ -8,7 +8,7 @@ weight: 100
 
 ## read
 
-`read(filepath: string) -> str`
+`read(filepath: str) -> str`
 
 Read the contents of the file `filepath` and return a string instance.
 
@@ -29,3 +29,15 @@ Return the root path of the current KCL module (kcl.mod file path or single \*.k
 `workdir() -> str`
 
 Return the path of the current working directory.
+
+## exists
+
+`exists(filepath: str) -> bool`
+
+Whether this file path exists. Returns true if the path points at an existing entity. This function will traverse symbolic links to query information about the destination file.
+
+## abs
+
+`abs(filepath: str) -> str`
+
+Returns the canonical, absolute form of the path with all intermediate components normalized and symbolic links resolved.

i18n/zh-CN/docusaurus-plugin-content-docs/current/reference/model/file.md

@@ -8,7 +8,7 @@ weight: 100
 
 ## read
 
-`read(filepath: string) -> str`
+`read(filepath: str) -> str`
 
 读取文件 `filepath` 中的内容，并返回一个字符串实例。
 
@@ -29,3 +29,15 @@ weight: 100
 `workdir() -> str`
 
 返回当前工作目录的路径。
+
+## exists
+
+`exists(filepath: str) -> bool`
+
+判断文件路径是否存在。如果路径指向一个存在的实体，则返回 True。此函数会遍历符号链接以查询目标文件的信息。
+
+## abs
+
+`abs(filepath: str) -> str`
+
+返回路径的规范化绝对形式，其中所有中间路径均已规范化并解析为符号链接。