Rename md docs to lowercase

docs/configuration.md

@@ -145,7 +145,7 @@ Here is another example with a few function signatures:
 
 ## Operator()
 
-This options defines an [operator overloading](Operator-Overloading.md).
+This options defines an [operator overloading](operator-overloading).
 
 ## Optimize()
 
@@ -153,4 +153,4 @@ This option enables [optimizations](Internals.md). By default, Expr will optimiz
 
 ## Patch()
 
-This option allows you to [patch the expression](Visitor-and-Patch.md) before compilation.
+This option allows you to [patch the expression](visitor-and-patch) before compilation.

docs/getting-started.md

@@ -73,7 +73,7 @@ if err != nil {
 Expr can work with any Go types. Here is an example:
 
 ```go
-env := map[string]interface{}{
+env := map[string]any{
 	"greet":   "Hello, %v!",
 	"names":   []string{"world", "you"},
 	"sprintf": fmt.Sprintf,