cleanup, docs

site/doc/pages/file_pwrite.txt

@@ -1,11 +1,26 @@
-file_pwrite
+:sig
+u64 file_pwrite(u64 h, u64 offset, String data)
 
-Streaming/handle-based file I/O across the wasm host membrane. Handles are opaque u64 values returned by file_open(); 0 means open failed (including path policy denial or bounded lock timeout). Locks are automatic and lifetime-scoped: read opens take a shared lock, write/append/read-write opens take an exclusive lock, and file_close() releases it. Lock wait is bounded by UCE_FILE_LOCK_TIMEOUT_MS (default 2000ms).
+:params
+h : handle from file_open() opened for writing
+offset : absolute byte offset to write at
+data : bytes to write
+return value : number of bytes written
 
-See also: file_get_contents, file_put_contents, file_append.
+:content
+Writes `data` at an absolute `offset` without moving the handle's current offset. The handle must be opened with a writable mode (`"r+"` for in-place edits).
+
+:example
+u64 h = file_open("/tmp/doc-pwrite.txt", "w");
+file_write(h, "hello world");
+file_close(h);
+u64 e = file_open("/tmp/doc-pwrite.txt", "r+");
+file_pwrite(e, 6, "earth");
+file_close(e);
+print(file_get_contents("/tmp/doc-pwrite.txt"), "\n");
 
 :see
 >sys
-
-:example
-print("file_pwrite example\n");
+file_write
+file_pread
+file_open