Add the PCRE library preface to the BSD-3 license

PiperOrigin-RevId: 429651776
diff --git a/v2/assets/Supplement/BSD-3-Clause/preface-pcre.txt b/v2/assets/Supplement/BSD-3-Clause/preface-pcre.txt
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+PCRE LICENCE
+------------
+
+PCRE is a library of functions to support regular expressions whose syntax
+and semantics are as close as possible to those of the Perl 5 language.
+
+Release 8 of PCRE is distributed under the terms of the "BSD" licence, as
+specified below. The documentation for PCRE, supplied in the "doc"
+directory, is distributed under the same terms as the software itself. The data
+in the testdata directory is not copyrighted and is in the public domain.
+
+The basic library functions are written in C and are freestanding. Also
+included in the distribution is a set of C++ wrapper functions, and a
+just-in-time compiler that can be used to optimize pattern matching. These
+are both optional features that can be omitted when the library is built.
+
+
+THE BASIC LIBRARY FUNCTIONS
+---------------------------
+
+Written by:       Philip Hazel
+Email local part: ph10
+Email domain:     cam.ac.uk
+
+University of Cambridge Computing Service,
+Cambridge, England.
+
+Copyright (c) 1997-2015 University of Cambridge
+All rights reserved.
+
+
+PCRE JUST-IN-TIME COMPILATION SUPPORT
+-------------------------------------
+
+Written by:       Zoltan Herczeg
+Email local part: hzmester
+Emain domain:     freemail.hu
+
+Copyright(c) 2010-2015 Zoltan Herczeg
+All rights reserved.
+
+
+STACK-LESS JUST-IN-TIME COMPILER
+--------------------------------
+
+Written by:       Zoltan Herczeg
+Email local part: hzmester
+Emain domain:     freemail.hu
+
+Copyright(c) 2009-2015 Zoltan Herczeg
+All rights reserved.
+
+
+THE C++ WRAPPER FUNCTIONS
+-------------------------
+
+Contributed by:   Google Inc.
+
+Copyright (c) 2007-2012, Google Inc.
+All rights reserved.
+
+
+THE "BSD" LICENCE
+-----------------