update README

README

@@ -1,9 +1,10 @@
---------SZ (version 2.0.0): Error-bounded Lossy Compressor for HPC Data--------
+--------SZ (version 2.1.0): Error-bounded Lossy Compressor for HPC Data--------
  (C) 2016 by Mathematics and Computer Science (MCS), Argonne National Laboratory.
        See COPYRIGHT in top-level directory.
 
-***Authors: Sheng Di, Dingwen Tao, Xin Liang ***
-***Supervisor: Franck Cappello ***
+*** Major Authors: Sheng Di, Dingwen Tao, Xin Liang ***
+*** Supervisor: Franck Cappello ***
+*** Other Contributors: Robert Underwood, Sihuan Li, Ali M. Gok, Xiangyu Zou, Tao Lu, Wen Xia, Xuan Wang, Weizhe Zhang ***
 
 =================================
 This document simply introduces how to install and use the SZ compressor. More details can be found in doc/userguide.pdf.
@@ -30,6 +31,10 @@ Then, you'll find all the executables in [INSTALL_DIR]/bin and .a and .so librar
 
 Examples can be found in the [SZ_PACKAGE]/example
 
+You can use the executable 'sz' command to do the compression/decompression. Please see the user guide or run 'sz --help' for details.
+
+Alternatively, you can also also call our API to do the compression/decompressoin. Here are two examples: testfloat_compress.c and testfloat_decompress.c
+
 ===Compress===
 --------------
 ./test_compress sz.config testdouble_8_8_8_128.dat 8 8 8 128
@@ -90,7 +95,7 @@ public static double[] SZ_decompress(byte[] bytes, size_t r5, size_t r4, size_t
 
 ===Limitation of this version===
 --------------------------------
-SZ is not suitable for compressing tiny datastes (such as the size <1MB)
+SZ is not suitable for compressing tiny datastes (such as the size <20KB)
 
 ===version history===
 ---------------------
@@ -143,3 +148,4 @@ SZ 1.4.13.5: remove the pwrType in SZ_compress_args() interface, because of usel
 SZ 2.0.0.0: Significantly improve the compression quality for the high-compression cases (i.e., improve the PSNR for the cases with high compression ratios)
 SZ 2.0.1.0: Further improve the compression quality for high-compression cases than 2.0.0.0. Moreover, improve point-wise relative error bounded compression.
 SZ 2.0.2.0: Further improve the compression/decompression rate and also compression ratio (by 10-20%), by replacing Zlib by Zstd as default setting.
+SZ 2.1: Significantly improve the compressoin speed for point-wise relative error bound (please see our paper published in MSST19 for details)