Having a true plain text editor

Is your feature request related to a problem? Please describe.
I don't use markdown I usually do asciidoc and custom formated plaintext. When I open this file the editor impones markdown symtax and tries to preview it.

Describe the solution you'd like
Loading custom exention and .txt in a "plain" editor with no formatting and preview but only text.

Describe alternatives you've considered
I could do with other app would be great having a multiplatform option.

Additional context
I find it frustrating viewing plain text, when random characters are recognised as markup and the note is immediately formatted, with ugly results. And, annoyingly, there is no way to turn this off.

I know many people love markup, but some of us that just want to work with plain text. Some apps that used to work perfectly for us, are now just butchering our notes with random formatting.

I could re-format my notes to remove/escape markup but:

• if you ever paste source code, or, say, a bash script, into a text editor you will often find it re-formatted to be unreadable
• I don't want to do that

I have built a "forked" version that turns off all markup functionality, and it covers my use case perfectly.

Is it worth my while adding an option in Settings to turn off markup across the board, similar to the monospace font option, and creating a Pull Request?

Start by reviewing the Android editor and Settings entry points to understand how Markdown formatting, preview, and file extensions are selected. The work would be complete when a setting or equivalent option provides an unformatted text editor for .txt and custom extensions without markup processing or preview; no specific files or tests are named in the issue.