fix: correct map doc to remove nonexistent iterate/iteratorValue and fix remove param formatting

- Remove erroneous iterate() and iteratorValue() method docs from map.markdown
  since Map does not expose those methods directly
- Fix remove(key) parameter formatting from [key] to `key` for consistency
- Correct File.read encoding description from "The encoding or decoding is done"
  to "No encoding or decoding is done" to accurately reflect behavior

doc/site/modules/io/file.markdown

@@ -47,7 +47,7 @@ Reads the entire contents of the file at `path` and returns it as a string.
     :::wren
     File.read("words.txt")
 
-The encoding or decoding is done. If the file is UTF-8, then the resulting
+No encoding or decoding is done. If the file is UTF-8, then the resulting
 string will be a UTF-8 string. Otherwise, it will be a string of bytes in
 whatever encoding the file uses.