Merging r326195:

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r326195 | hans | 2018-02-27 14:48:50 +0100 (Tue, 27 Feb 2018) | 1 line

AttrDocs.td: fix some bad code-blocks
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_60@326196 91177308-0d34-0410-b5e6-96231b3b80d8