docs: fix a few string quoting bits (#27)

README.md

@@ -70,7 +70,7 @@ See [GRAMMAR.md](./GRAMMAR.md) for a more complete documentation of [mql](https:
 
 Example query:
 
-`name="alice" and age > 11 and (region % Boston or region="south shore")`
+`name="alice" and age > 11 and (region % 'Boston' or region="south shore")`
 
 ### Date/Time fields
 

docs.go

@@ -9,15 +9,15 @@
 //
 // Gorm: https://github.com/go-gorm/gorm
 //
-//	w, err := mql.Parse("name=alice or name=bob)",User{})
+//	w, err := mql.Parse(`name="alice" or name="bob"`,User{})
 //	if err != nil {
 //	  return nil, err
 //	}
 //	err = db.Where(w.Condition, w.Args...).Find(&users).Error
 //
 // database/sql: https://pkg.go.dev/database/sql
 //
-//	w, err := mql.Parse("name=alice or name=bob)",User{})
+//	w, err := mql.Parse(`name="alice" or name="bob"`,User{})
 //	if err != nil {
 //	  return nil, err
 //	}
@@ -26,7 +26,7 @@
 //
 // go-dbw: https://github.com/hashicorp/go-dbw
 //
-//	w, err := mql.Parse("name=alice or name=bob)",User{})
+//	w, err := mql.Parse(`name="alice" or name="bob")`,User{})
 //	if err != nil {
 //	  return nil, err
 //	}
@@ -41,7 +41,9 @@
 // Fields in your model can be compared with the following operators:
 // =, !=, >=, <=, <, >, %
 //
-// Double quotes `"` can be used to quote strings.
+// Strings must be quoted. Double quotes ", single quotes ' or backticks ` can
+// be used as delimiters. Users can choose whichever supported delimiter makes
+// it easier to quote their string.
 //
 // Comparison operators can have optional leading/trailing whitespace.
 //
@@ -58,5 +60,5 @@
 //
 // Example query:
 //
-//	name=alice and age > 11 and (region % Boston or region="south shore")
+//	name="alice" and age > 11 and (region % "Boston" or region="south shore")
 package mql