builtin: rename any_* -> *_literal - 2. part (#8032)

doc/docs.md

@@ -371,8 +371,6 @@ rune // represents a Unicode code point
 
 f32 f64
 
-any_int, any_float // internal intermediate types of number literals
-
 byteptr, voidptr, charptr, size_t // these are mostly used for C interoperability
 
 any // similar to C's void* and Go's interface{}
@@ -400,6 +398,21 @@ or `i64` but not to `f32` or `u32`. (`f32` would mean precision
 loss for large values and `u32` would mean loss of the sign for
 negative values).
 
+Literals like `123` or `4.56` are treated in a special way. They do
+not lead to type promotions, however they default to `int` and `f64`
+respectively, when their type has to be decided:
+
+```v ignore
+u := u16(12)
+v := 13 + u    // v is of type `u16` - no promotion
+x := f32(45.6)
+y := x + 3.14  // x is of type `f32` - no promotion
+a := 75        // a is of type `int` - default for int literal
+b := 14.7      // b is of type `f64` - default for float literal
+c := u + a     // c is of type `int` - automatic promotion of `u`'s value
+d := b + x     // d is of type `f64` - automatic promotion of `x`'s value 
+```
+
 ### Strings
 
 ```v