[doc] Fix regex in ClangFormatStyleOptions for IncludeCategories

This fixes the regex in ClangFormatStyleOptions for IncludeCategories
to match anything starting with < or starting with | AND followed by
(gtest|gmock|isl|json) then /.

Differential Revision: https://reviews.llvm.org/D115910

clang/docs/ClangFormatStyleOptions.rst

@@ -2457,7 +2457,7 @@ the configuration (without a prefix: ``Auto``).
         Priority:        2
         SortPriority:    2
         CaseSensitive:   true
-      - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
+      - Regex:           '^((<|")(gtest|gmock|isl|json)/)'
         Priority:        3
       - Regex:           '<[[:alnum:].]+>'
         Priority:        4

clang/include/clang/Tooling/Inclusions/IncludeStyle.h

@@ -106,7 +106,7 @@ struct IncludeStyle {
   ///       Priority:        2
   ///       SortPriority:    2
   ///       CaseSensitive:   true
-  ///     - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
+  ///     - Regex:           '^((<|")(gtest|gmock|isl|json)/)'
   ///       Priority:        3
   ///     - Regex:           '<[[:alnum:].]+>'
   ///       Priority:        4