docs: fixed code highlight in README.md

README.md

@@ -274,7 +274,7 @@ lualine.sections.lualine_b = {
 You can use lualine to display components in tabline.
 The sections, configurations and highlights are same as statusline.
 
-```
+```lua
 lualine.tabline = {
   lualine_a = { },
   lualine_b = { 'branch' },
@@ -289,7 +289,7 @@ This will show branch and filename component in top of neovim inside tabline .
 
 You can also completely move your statuline to tabline by configuring lualine.tabline
 instead of lualine.sections & lualine.inactive_sections and setting them to empty
-```
+```lua
 lualine.tabline = {
 ......
   }