cleanup, docs

site/doc/pages/file_copy.txt

@@ -1,9 +1,20 @@
-file_copy
+:sig
+bool file_copy(String from, String to)
 
-Structural filesystem operation across the wasm host membrane. All path arguments are policy-gated through the same guest file/write roots as other file APIs and return false on denial or OS error.
+:params
+from : source path
+to : destination path (overwritten if it exists)
+return value : true on success
+
+:content
+Copies a file's contents to a new path, overwriting the destination if present.
+
+:example
+file_put_contents("/tmp/doc-copy-src.txt", "payload");
+file_copy("/tmp/doc-copy-src.txt", "/tmp/doc-copy-dst.txt");
+print(file_get_contents("/tmp/doc-copy-dst.txt"), "\n");
 
 :see
 >sys
-
-:example
-print("file_copy example\n");
+file_rename
+file_put_contents