'themes/half-life.zsh-theme: Solve typos'

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

themes/half-life.zsh-theme

@@ -17,7 +17,7 @@ setopt prompt_subst
 autoload -U add-zsh-hook
 autoload -Uz vcs_info
 
-#use extended color pallete if available
+#use extended color palette if available
 if [[ $TERM = *256color* || $TERM = *rxvt* ]]; then
     turquoise="%F{81}"
     orange="%F{166}"