[docs] Remove accidental unindent to appease the sphinx bot

Bot failure:
http://lab.llvm.org:8011/builders/clang-sphinx-docs/builds/12043/steps/docs-clang-html/logs/stdio

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@309852 91177308-0d34-0410-b5e6-96231b3b80d8

Author: vedantk

docs/UndefinedBehaviorSanitizer.rst

@@ -132,10 +132,10 @@ Available checks are:
   -  ``-fsanitize=vla-bound``: A variable-length array whose bound
      does not evaluate to a positive value.
   -  ``-fsanitize=vptr``: Use of an object whose vptr indicates that it is of
-    the wrong dynamic type, or that its lifetime has not begun or has ended.
-    Incompatible with ``-fno-rtti``. Link must be performed by ``clang++``, not
-    ``clang``, to make sure C++-specific parts of the runtime library and C++
-    standard libraries are present.
+     the wrong dynamic type, or that its lifetime has not begun or has ended.
+     Incompatible with ``-fno-rtti``. Link must be performed by ``clang++``, not
+     ``clang``, to make sure C++-specific parts of the runtime library and C++
+     standard libraries are present.
 
 You can also use the following check groups:
   -  ``-fsanitize=undefined``: All of the checks listed above other than