Document direction option

Exists since commit 3c18925, codemirror#4624

Author: cben

doc/manual.html

@@ -292,6 +292,17 @@ <h2>Configuration</h2>
       character. By default, a red dot (<span style="color: red">•</span>)
       is shown, with a title tooltip to indicate the character code.</dd>
 
+      <dt id="option_direction"><code><strong>direction</strong>: "ltr" | "rtl"</code></dt>
+      <dd>Flips overall layout and selects base paragraph direction to
+      be left-to-right or right-to-left.  Default is "ltr".
+      CodeMirror applies the Unicode Bidirectional Algorithm to each
+      line, but does not autodetect base direction — it's set to the
+      editor direction for all lines.  The resulting order is
+      sometimes wrong when base direction doesn't match user intent
+      (for example, leading and trailing punctuation jumps to the
+      wrong side of the line).  Therefore, it's helpful for
+      multilingual input to let users toggle this option.
+
       <dt id="option_rtlMoveVisually"><code><strong>rtlMoveVisually</strong>: boolean</code></dt>
       <dd>Determines whether horizontal cursor movement through
       right-to-left (Arabic, Hebrew) text is visual (pressing the left