[ docs ] Fix #1367: Missing spaces in type signatures in WebKit-based browsers

WebKit seems to throw away any sequence of spaces between inline tags.
All affected places I found could be fixed by replacing single space
characters with the character U+2002 ("EN Space"), which means
almost the same thing as "normal space" (i.e. it breaks/wraps text and
has approximately the same width) but is not discarded by WebKit when
parsing the document.

If this should come up in a different place, a more thorough solution
might be needed (e.g. modifying `htmlEscape` to replace all spaces).

src/Idris/Doc/HTML.idr

@@ -51,6 +51,7 @@ renderHtml : {auto c : Ref Ctxt Defs} ->
              SimpleDocTree IdrisDocAnn ->
              Core String
 renderHtml STEmpty = pure neutral
+renderHtml (STChar ' ') = pure " "
 renderHtml (STChar c) = pure $ cast c
 renderHtml (STText _ text) = pure text
 renderHtml (STLine _) = pure "<br>"