Tweak warning color for gruvbox_light theme

[Locorock]

The current behaviour of the theme grubox_light is for the warnings to be written using the orange1 color, when it should be yellow1 instead, according to the original gruvbox vim theme at https://github.com/morhetz/gruvbox. We can see an example on how it should look here:

How it currently looks with orange1 as warning:

and how it would look with "warning" = { fg = "yellow1" }:

I know it doesn't look much different but the contrast between error and warning benefits greatly from this change

[RoloEdits]

Hmm, gruvbox_light inherits from gruvbox for most things, including the colors of the diagnostic highlights.

This is what is currently defined:

"warning" = "orange1"
"error" = "red1"
"info" = "aqua1"
"hint" = "blue1"

This is what I found in in the gruvbox repo:

call s:HL('CocErrorHighlight', s:none, s:none, s:undercurl, s:red)
call s:HL('CocWarningHighlight', s:none, s:none, s:undercurl, s:orange)
call s:HL('CocInfoHighlight', s:none, s:none, s:undercurl, s:yellow)
call s:HL('CocHintHighlight', s:none, s:none, s:undercurl, s:blue)

From this, the outlier seems to be info.

I may be misunderstanding what you mean though.

[Locorock]

This seems to be the case for CoC, but oddly enough only for CoC.
and not for Syntastic:

call s:HL('SyntasticError', s:none, s:none, s:undercurl, s:red)
call s:HL('SyntasticWarning', s:none, s:none, s:undercurl, s:yellow)

or ALE:

call s:HL('ALEError', s:none, s:none, s:undercurl, s:red)
call s:HL('ALEWarning', s:none, s:none, s:undercurl, s:yellow)
call s:HL('ALEInfo', s:none, s:none, s:undercurl, s:blue)

and the screenshots clearly show yellow as being used for warnings

[RoloEdits]

Huh, weird. Well I guess with the majority using yellow, and stated improved contrast, might as well change them all over to yellow. Let me do a quick check for all the themes and see if the base gruvbox can just be changed over and propagated and have an easy single file change, and I can get up a pr for this.