add documentation for remove emoji

[jazzsequence]

• adds documentation for the remove-emoji module

See #96

[hm-linter]

Linting failed (4 errors).

4 notices occurred in your codebase, but none on files/lines included in this PR.

[roborourke]

I'm kind of in 2 minds here. In the original issue I think I chose a bad name for the config option. Talking about removing emoji is a bit confusing and drastic sounding as we're really just removing the image replacement functionality. We'd need to be very clear about that in the wording throughout.

Do you think the general explanation of what emoji are and the details about the specific JS files that are no longer loaded might be more than is really needed? I think it just needs to explain that if your website might be run on systems that do not support emoji you can enable image replacements by setting this setting.

In a similar pattern to the search and SEO module docs maybe we could condense this into a small section on the main readme if there isn't enough to warrant a full page.

I might make an issue for renaming that config option first (we can keep back compat) but I think it'll help with making these docs clearer.

[jazzsequence]

@roborourke I think renaming the config option is a better first step. As you say, "remove emoji" sounds pretty drastic and misleading, and the description, I think, makes less sense if you go into it with that frame of reference. As such, we should punt this to 6.0 and make changing the option name a dependency of this.

[jazzsequence]

"To allow emojis" should be "To allow emoji image replacement"

[roborourke]

Created #260 for the setting name change