`direction in subgraph` syntax for `mermaid` is not supported

[mind1949]

Description

direction in subgraph syntax for mermaid is not supported.

To Reproduce

1. Write a simple mermaid flowcharts

flowchart TD
    A --> B
    subgraph TOP
      %% direction LR
      a --> b
   end

2. Open in preview mode

3. Remote comment at line 4

flowchart TD
    A --> B
    subgraph TOP
         direction LR
	 a --> b
    end

4. Open in preview mode

Expected behavior

FSNotes version

Version 5.3.3 (512)

macOS/iOS version

10.14.2

Additional context

No response