Fix Constraints docs

doc/src/constraints.md

@@ -5,7 +5,7 @@ assigned.
 
 While Formidable ships with a small set of constraints, these are primarily consumed by the `FieldMappingFactory`, so
 generally you will want to write your own constraints. To do so, create a new class which implements the
-`ConstaintInterface`. That class will have a single method `__invoke($value)`, which must return a `ValidationResult`.
+`ConstraintInterface`. That class will have a single method `__invoke($value)`, which must return a `ValidationResult`.
 In case an empty validation result is returned, it is considered successful.
 
 A constraint always gets the converted value passed. So in case of a field mapping, you'll get a scalar PHP value. In
@@ -47,7 +47,7 @@ $mapping = FieldMappingFactory::text()->verifying(new PatternConstraint());
     as you assign the constraint to the correct mapping , but since we do not have generics yet, you should actually
     assert the input type which you receive.
 
-    See [Assert package on Github](https://github.com/beberlei/assert)
+See [Assert package on Github](https://github.com/beberlei/assert)
 
 # Context validation
 
@@ -95,7 +95,7 @@ custom `PasswordConfirmationConstraint` class:
 new ValidationError('error.password-mismatch', [], 'passwordConfirm')
 ```
 
-The 'passwordConfirm' argument matches the key of one of the child mappings. This specifies which child mapping the
+The `passwordConfirm` argument matches the key of one of the child mappings. This specifies which child mapping the
 validation error should be attached to. If we omit that parameter, the error defaults to the parent object mapping. In
 case of a root mapping, this would have resulted in a global context for any password contstraint validation error. In
 some cases you might want to keep the global error context, but for cases where it is desirable to associate a