Fix link to duration months (#1232)

Author: elliott-king

src/duration.js

@@ -160,7 +160,7 @@ function normalizeValues(matrix, vals) {
  * Here is a brief overview of commonly used methods and getters in Duration:
  *
  * * **Creation** To create a Duration, use {@link Duration#fromMillis}, {@link Duration#fromObject}, or {@link Duration#fromISO}.
- * * **Unit values** See the {@link Duration#years}, {@link Duration.months}, {@link Duration#weeks}, {@link Duration#days}, {@link Duration#hours}, {@link Duration#minutes}, {@link Duration#seconds}, {@link Duration#milliseconds} accessors.
+ * * **Unit values** See the {@link Duration#years}, {@link Duration#months}, {@link Duration#weeks}, {@link Duration#days}, {@link Duration#hours}, {@link Duration#minutes}, {@link Duration#seconds}, {@link Duration#milliseconds} accessors.
  * * **Configuration** See  {@link Duration#locale} and {@link Duration#numberingSystem} accessors.
  * * **Transformation** To create new Durations out of old ones use {@link Duration#plus}, {@link Duration#minus}, {@link Duration#normalize}, {@link Duration#set}, {@link Duration#reconfigure}, {@link Duration#shiftTo}, and {@link Duration#negate}.
  * * **Output** To convert the Duration into other representations, see {@link Duration#as}, {@link Duration#toISO}, {@link Duration#toFormat}, and {@link Duration#toJSON}