display freeze overlay on target unit fix Update ui.lua

[Lagi7]

freeze method need to display first sprite (index 0) not 5th as web

[Lagi7]

to ilustrate what i talking here about:

the below ices on top of unit dont appear when you cast Freeze spell, because current code using frame nr 5 (index4) instead frame nr 1 (index 0)

[Lagi7]

[Lagi7]

Method = {method-name, {tag = value}}

<dd>Which method we use to show variable. It could be a bar, a sprite, a number...</dd>
<dl>
  <dt>"text", {}</dt>
  <dd>Show the value with a number</dd>
  <dt>"static-sprite", {"sprite-name**", number}</dt>
  <dd>Use the number icon of the sprite (**defined by <a href="#DefineSprites">DefineSprites()</a>)</dd>

line 429 https://github.com/Wargus/stratagus/blob/2636ea33d5a620be95afc9d867e10269cb991ac7/doc/scripts/config.html#L429