Add lang attribute to EDITING.md

[xfq]

Fix #213.

[xfq]

I added lang to the img elements as well, but they actually do not have the lang attributes in the current jlreq document. Should I remove them in EDITING.md, or do we need to add lang for the img elements (because it specifies the language for the text in alt)?

[himorin]

I think some img elements in JLreq Note has lang="ja" (but none for lang="en"?)

[r12a]

Thanks for preparing this @xfq . I think we should keep the recommendation to use the lang attribute for images too. As you say, this can be useful for alt or title text. I'm not sure whether we need to retrofit that to the jlreq doc, if it's currently working ok.

We should also change the advice about linking to sections and figures, to recommend use of [[[ ]]] rather than the <a> markup currently recommended.

[xfq]

Thanks for preparing this @xfq . I think we should keep the recommendation to use the lang attribute for images too. As you say, this can be useful for alt or title text. I'm not sure whether we need to retrofit that to the jlreq doc, if it's currently working ok.

OK. Could you merge this PR?

We should also change the advice about linking to sections and figures, to recommend use of [[[ ]]] rather than the <a> markup currently recommended.

I just submitted #221 for this.