add a README file to show credits of the sample files.

git-svn-id: https://pdfminerr.googlecode.com/svn/trunk/pdfminer@223 1aa58f4a-7d42-0410-adbc-911cccaed67c

samples/README

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+This directory contains sample PDF files.
+
+Here are the credits of the original files:
+
+dmca.pdf: 
+U.S. Copyright Office
+The Digital Millenium Copyright Act
+http://www.copyright.gov/legislation/dmca.pdf
+
+f1040nr.pdf:
+U.S. Department of the Treasury Internal Revenue Service
+Form 1040-NR, U.S. Nonresident Alien Income Tax Return
+http://www.irs.gov/pub/irs-pdf/f1040nr.pdf
+
+i1040nr.pdf:
+U.S. Department of the Treasury Internal Revenue Service
+Instructions for Form 1040-NR, U.S. Nonresident Alien Income Tax Return
+http://www.irs.gov/pub/irs-pdf/i1040nr.pdf
+
+jo.pdf:
+Kenji Miyazawa (1896-1933, copyright expired)
+Preface of "Haru to Shura"
+(File generated by LaTeX and dvi2pdfm)
+
+kampo.pdf:
+National Priting Bureau of Japan
+Official Gazette, Vol. 4817
+http://kanpou.npb.go.jp/
+
+nlp2004slides.pdf:
+Yusuke Shinyama and Satoshi Sekine
+"Named Entity Discovery from Comparable News Corpora"
+
+naacl06-shinyama.pdf:
+Yusuke Shinyama and Satoshi Sekine
+"Preemptive Information Extraction using Unrestircted Relation Discovery"
+
+simple1.pdf:
+(Originally taken from PDF Specification, 
+Appendix G. "Simple Text String Example" and modified)
+
+simple2.pdf:
+(Originally taken from PDF Specification, 
+Appendix G. "Simple Graphics Example" and modified)