[clang-tidy][doc] Fix broken CppCoreGuidelines links

They recently changed all their anchors to start with lowercase:
isocpp/CppCoreGuidelines#2304

So now our links are broken :) This patch fixes them.

Author: Carlos Gálvez

clang-tools-extra/docs/clang-tidy/checks/bugprone/switch-missing-default-case.rst

@@ -51,6 +51,6 @@ Example:
    on non-enum types where the compiler warnings may not be present.
 
 .. seealso::
-   The `CppCoreGuideline ES.79 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-default>`_
+   The `CppCoreGuideline ES.79 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#res-default>`_
    provide guidelines on switch statements, including the recommendation to
    always provide a default case.

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-capturing-lambda-coroutines.rst

@@ -8,7 +8,7 @@ use-after-free errors and suggests avoiding captures or ensuring the lambda
 closure object has a guaranteed lifetime.
 
 This check implements `CP.51
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rcoro-capture>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rcoro-capture>`_
 from the C++ Core Guidelines.
 
 Using coroutine lambdas with non-empty capture lists can be risky, as capturing

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-const-or-ref-data-members.rst

@@ -44,7 +44,7 @@ Examples:
   };
 
 This check implements `C.12
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rc-constref>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rc-constref>`_
 from the C++ Core Guidelines.
 
 Further reading:

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-do-while.rst

@@ -9,7 +9,7 @@ condition is not checked prior to the first iteration.
 This can lead to subtle bugs.
 
 This check implements `ES.75
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-do>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#res-do>`_
 from the C++ Core Guidelines.
 
 Examples:

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

@@ -6,7 +6,7 @@ cppcoreguidelines-avoid-non-const-global-variables
 Finds non-const global variables as described in `I.2
 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#i2-avoid-non-const-global-variables>`_
 of C++ Core Guidelines.
-As `R.6 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rr-global>`_
+As `R.6 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rr-global>`_
 of C++ Core Guidelines is a duplicate of rule `I.2
 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#i2-avoid-non-const-global-variables>`_
 it also covers that rule.

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-reference-coroutine-parameters.rst

@@ -18,5 +18,5 @@ Examples:
   }
 
 This check implements `CP.53
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rcoro-reference-parameters>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rcoro-reference-parameters>`_
 from the C++ Core Guidelines.

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/init-variables.rst

@@ -8,8 +8,8 @@ value. These may lead to unexpected behavior if there is a code path that reads
 the variable before assigning to it.
 
 This rule is part of the `Type safety (Type.5)
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Pro-type-init>`_
-profile and `ES.20 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-always>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#pro-type-init>`_
+profile and `ES.20 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#res-always>`_
 from the C++ Core Guidelines.
 
 Only integers, booleans, floats, doubles and pointers are checked. The fix

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/interfaces-global-init.rst

@@ -7,7 +7,7 @@ This check flags initializers of globals that access extern objects,
 and therefore can lead to order-of-initialization problems.
 
 This check implements `I.22
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Ri-global-init>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#ri-global-init>`_
 from the C++ Core Guidelines.
 
 Note that currently this does not flag calls to non-constexpr functions, and

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/missing-std-forward.rst

@@ -43,5 +43,5 @@ Options
    Specify the function used for forwarding. Default is `::std::forward`.
 
 This check implements `F.19
-<http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rf-forward>`_
+<http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rf-forward>`_
 from the C++ Core Guidelines.

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/no-malloc.rst

@@ -10,7 +10,7 @@ Furthermore, it can be configured to check against a user-specified list of
 functions that are used for memory management (e.g. ``posix_memalign()``).
 
 This check implements `R.10
-<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rr-mallocfree>`_
+<https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#rr-mallocfree>`_
 from the C++ Core Guidelines.
 
 There is no attempt made to provide fix-it hints, since manual resource