Docstrings examples for string methods (#7669)

* Use more descriptive link texts

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* Fix link target name

* Fix typos

* Add example for DataArray.str.capitalize

* Add example for DataArray.str.lower

* Add docstring example for DataArray.str.swapcase

* Add docstring example for DataArray.str.title

* Add docstring example for DataArray.str.upper

* Add docstring example for DataArray.str.casefold

* Add docstring example for DataArray.str.isalnum

* Add docstring example for DataArray.str.isalpha

* Add docstring example for DataArray.str.isdecimal

* Add docstring example for DataArray.str.isdigit

* Add docstring example for DataArray.str.islower

* Add docstring example for DataArray.str.isnumeric

* Add docstring example for DataArray.str.isspace

* Add docstring example of DataArray.str.istitle

* Add docstring example for DataArray.str.isupper

* Add a docstring example for DataArray.str.count

* Add docstring example of DataArray.str.startswith

* Add docstring example of DataArray.str.endswith

* Use varied examples

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* Escape \n and \t

Solves the incosistent whitespace error

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* Fixes failing doctests

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* Replace "Example" with "Examples"

To follow the Numpy docstrings format.

* Delete unnecessary import

* Pass a regex to the count function

* Pass an array of strings to the count function

This example demonstrates how the pattern is broadcasted.

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* Add docstrings examples for DataArray.str.pad

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* Fix invalid escape sequence warning

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* Fix regex

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* Add data array and filled value

* Correct spelling mistake

* Modify wording to make it easier to understand

* Fix indent errors

* Add whats-new, fix docs

---------

Co-authored-by: remigathoni <marg.kahiga@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Deepak Cherian <dcherian@users.noreply.github.com>

doc/whats-new.rst

@@ -38,7 +38,9 @@ Bug fixes
 
 Documentation
 ~~~~~~~~~~~~~
-
+- Added examples to docstrings for :py:meth:`xarray.core.accessor_str.StringAccessor` methods.
+  (:pull:`7669`) .
+  By `Mary Gathoni <https://github.com/remigathoni>`_.
 
 Internal Changes
 ~~~~~~~~~~~~~~~~