As a programmer, it is up to you how you integrate and access a ‘Help section’ in your programme.
My suggestion:
From my own experience, I would advise you to put such explanations in a separate PDF document, store it in the app's assets and call it up separately in a window. Alternatively, you can also use BB code, but this is not nearly as convenient to programme.
The PDF file can be easily created with Microsoft Word. This has the advantage that you can also incorporate screenshots with text wraps into the document. At the beginning of the document, there should be a table of contents with links to the corresponding passages in the text. Then simply export the finished file as a PDF file; the links will remain intact.
Using this principle, you can also quickly keep the documentation for your app up to date when there are programme changes.
All you need to do is integrate a suitable PDF viewer into your programme. Done.
Of course, you will encounter a problem if your app supports multiple languages. Either you only offer an English version or you load a file with explanations in the appropriate language depending on the default language set on the device. Deepl does the translations for you very reliably.
Cheers, BV