[clang-tidy][doc] Remove unused variable

[bjosv]

Summary

Remove mention of a variable that is not used in the example for checker:
cppcoreguidelines-avoid-non-const-global-variables

[Eugene.Zelenko]

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst

34–35

Please fill as much of 80 symbols as possible.

[bjosv]

Updated to fill 80 char as proposed, and changed some wordings.

[carlosgalvezp]

LGTM, thanks for the fix!

[carlosgalvezp]

@bjosv Are you able to land the patch yourself, or should we do it for you? If so, please provide user and email for Github attribution.

[bjosv]

@carlosgalvezp Sorry, I should have mentioned that I don't have push rights and that this is my first contribution to llvm.
My GitHub user is: bjosv and email: [e-mail]
Thanks.

[carlosgalvezp]

In D143996#4147759, @bjosv wrote:

@carlosgalvezp Sorry, I should have mentioned that I don't have push rights and that this is my first contribution to llvm.
My GitHub user is: bjosv and email: [e-mail]
Thanks.

No problem, thanks for your first contribution! :)

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables.rst

.. code-block:: c++
     public:
         char e = 0;
         const char f = 0;
     protected:
         char g = 0;
     private:
         char h = 0;
     };
 
-Variables: ``a``, ``c``, ``c_ptr1``, ``c_ptr2``, ``c_const_ptr`` and
-``c_reference``, will all generate warnings since they are either:
-a globally accessible variable and non-const, a pointer or reference providing
-global access to non-const data or both.
+The variables ``a``, ``c``, ``c_ptr1``, ``c_const_ptr`` and ``c_reference``
+will all generate warnings since they are either a non-const globally accessible
+variable, a pointer or a reference providing global access to non-const data
+or both.