docs: add docs to Decode func

pkg/miniparse/miniparse.go

@@ -28,6 +28,23 @@ var (
 
 // Decode .mini config file into value using reflect.
 // The mini format is similar to ini, but very strict.
+//
+// Each line of the config must be one of the following: blank, comment, record title, record field.
+// Leading spaces are not allowed. End-of-line spaces are only allowed in record field lines.
+// A non-empty .mini config file must end with a blank string.
+// A comment must begin with a '#' character. All comments will be ignored by the parser.
+// The record title must be "[title]", where title is the non-empty name of the varname.
+// Varnames contain only lowercase ascii letters, digits and the '_' character.
+// The first letter of the varname must not be a digit.
+// The record field must have the form “key = value”, where key is a non-empty varname.
+// The value contains any valid utf-8 sequence.
+// Record names and keys can be non-unique. Then they will be interpreted as arrays.
+//
+// The mini format does not specify data types of values.
+// But this decoder works only with string, int, bool and time.Duration.
+// You should use `mini:"name"` tag to designate a structure field.
+// You can use the `mini-required:"true"` tag for mandatory fields.
+// You can use the `mini-default:"value"` tag for default values.
 func Decode(r io.Reader, v any) error {
 	rb := bufio.NewReader(r)
 	m := newMachine()