fix typo (on -> one)

doc/modules/svm.rst

@@ -142,7 +142,7 @@ Note that the :class:`LinearSVC` also implements an alternative multi-class
 strategy, the so-called multi-class SVM formulated by Crammer and Singer, by
 using the option ``multi_class='crammer_singer'``. This method is consistent,
 which is not true for one-vs-rest classification.
-In practice, on-vs-rest classification is usually preferred, since the results
+In practice, one-vs-rest classification is usually preferred, since the results
 are mostly similar, but the runtime is significantly less.
 
 For "one-vs-rest" :class:`LinearSVC` the attributes ``coef_`` and ``intercept_``