typo fixed
There was typo in merging documentation ,fixed it now
A typo is fixed in  pandas documentation  particulary in user guide of  [Merge, join, concatenate and compare](https://pandas.pydata.org/docs/dev/user_guide/merging.html#) section   . Quoting a line from docs where a minor change has been done for clarity

**Earlier:**  

You can [Series](https://pandas.pydata.org/docs/dev/reference/api/pandas.Series.html#pandas.Series) and a [DataFrame](https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.html#pandas.DataFrame) with a [MultiIndex](https://pandas.pydata.org/docs/dev/reference/api/pandas.MultiIndex.html#pandas.MultiIndex) if the names of the [MultiIndex](https://pandas.pydata.org/docs/dev/reference/api/pandas.MultiIndex.html#pandas.MultiIndex) correspond to the columns from the [DataFrame](https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.html#pandas.DataFrame).

**Now:**

You can **merge** [Series](https://pandas.pydata.org/docs/dev/reference/api/pandas.Series.html#pandas.Series) and a [DataFrame](https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.html#pandas.DataFrame) with a [MultiIndex](https://pandas.pydata.org/docs/dev/reference/api/pandas.MultiIndex.html#pandas.MultiIndex) if the names of the [MultiIndex](https://pandas.pydata.org/docs/dev/reference/api/pandas.MultiIndex.html#pandas.MultiIndex) correspond to the columns from the [DataFrame](https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.html#pandas.DataFrame).

without **merge** word sentence is not making any sense 