Added default theme (#960)

* feat: Added default theme

* Revert "feat: Added default theme"

This reverts commit a11a99f92a.

* feat: Add basic theme feature

* feat: Add theme settings

* fix: Fix default theme value

* fix: Fix CR and doc-string

* Comment out darkMode on exampleSite/hugo.yaml

Signed-off-by: hossainemruz <hossainemruz@gmail.com>

---------

Signed-off-by: hossainemruz <hossainemruz@gmail.com>
Co-authored-by: Emruz Hossain <hossainemruz@gmail.com>

exampleSite/hugo.yaml

@@ -91,9 +91,19 @@ params:
   # Configure various features of this theme
   features:
 
-    # Enable dark theme
-    darkMode:
+    # [Deprecated] Enable dark theme
+    # This is a deprecated setting, but has not been removed to maintain backward compatibility
+    # If `theme` is set, the `darkMode` setting will be discarded.
+    # darkMode:
+    #   enable: true
+
+    # Configure theme color settings
+    theme:
       enable: true
+      services:
+        light: true # enable light theme. default "true"
+        dark: true # enable dark theme. default "true"
+        default: system # can be either light, dark or system. default "system"
 
     # Enable and configure portfolio
     portfolio: