Update README.md

README.md

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 # dshash
 
 Simple SHA256 hashing library and example utility
+
+## dshash C++ class
+
+- located in src/
+- A simple implementation of SHA256 with no dependencies.
+- Just two files: dshash.cpp and dshash.hpp
+- can hash a file, directory tree, or string.
+- uses std::array<uint8_t, 32> as the underlying type
+- generally used as a std::string, containing the hex representation of the hash.
+
+## dshash utility
+
+- located in dshash/
+- no dependencies, statically linked
+- simple command line utilty to calculate hash of file or directory
+- outputs the hash only with a newline
+- -v (verbose) mode lists the individual files as they are processed.
+
+# testing
+
+- testing of both the C++ class and the dshash utility are in tests/
+- ./test.sh runs all tests and returns success only if all pass.
+
+# publishing
+- dshash utility published as a getpkg.xyz package, and also available from getbin.xyz.
+