make alpha.nvim options structure match to all other plugin config options

this was creating confusion among people those who override alpha-nvim config

lua/plugins/configs/alpha.lua

@@ -34,9 +34,11 @@ local function button(sc, txt, keybind)
   }
 end
 
-local options = {}
+local options = {
 
-local ascii = {
+  header = {
+    type = "text",
+    val = {
       "   ⣴⣶⣤⡤⠦⣤⣀⣤⠆     ⣈⣭⣿⣶⣿⣦⣼⣆          ",
       "    ⠉⠻⢿⣿⠿⣿⣿⣶⣦⠤⠄⡠⢾⣿⣿⡿⠋⠉⠉⠻⣿⣿⡛⣦       ",
       "          ⠈⢿⣿⣟⠦ ⣾⣿⣿⣷    ⠻⠿⢿⣿⣧⣄     ",
@@ -48,18 +50,14 @@ local ascii = {
       " ⠙⠃   ⣼⣿⡟  ⠈⠻⣿⣿⣦⣌⡇⠻⣿⣿⣷⣿⣿⣿ ⣿⣿⡇ ⠛⠻⢷⣄ ",
       "      ⢻⣿⣿⣄   ⠈⠻⣿⣿⣿⣷⣿⣿⣿⣿⣿⡟ ⠫⢿⣿⡆     ",
       "       ⠻⣿⣿⣿⣿⣶⣶⣾⣿⣿⣿⣿⣿⣿⣿⣿⡟⢀⣀⣤⣾⡿⠃     ",
-}
-
-options.header = {
-  type = "text",
-  val = ascii,
+    },
     opts = {
       position = "center",
       hl = "AlphaHeader",
     },
-}
+  },
 
-options.buttons = {
+  buttons = {
     type = "group",
     val = {
       button("SPC f f", "  Find File  ", ":Telescope find_files<CR>"),
@@ -72,6 +70,7 @@ options.buttons = {
     opts = {
       spacing = 1,
     },
+  },
 }
 
 options = require("core.utils").load_override(options, "goolord/alpha-nvim")