add I example

examples/I/.gitignore

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+find_words

examples/I/Makefile

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+#
+# Makefile for finding words examples
+#
+OBJS = find_words.o
+LIBS = -lpmemobj -lpmem
+
+all: find_words
+
+find_words: $(OBJS)
+	$(CXX) $(CXXFLAGS) -o $@ $(OBJS) $(LIBS)
+
+clean:
+	$(RM) *.o core a.out
+
+clobber: clean
+	$(RM) find_words
+
+.PHONY: all clean clobber
+

examples/I/README.txt

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+C++ data structures in persistent memory
+
+In this example, we will solve a simple algorithmic problem using data
+structures which resides in persistent memory. We will use persistent containers
+from libpmemobj-cpp library.
+
+C++ programmers will get the most out of this example.
+
+This is example consists of these files:
+
+dictionary.txt       -- a file with some words which represents a dictionary
+board.txt            -- a file with characters in a form of 2D matrix
+Makefile             -- rules for building all the programs in this example
+trie.hpp             -- a simple trie structure implementation for persistent
+                        memory
+find_words.cpp       -- C++ program for finding words, program can continue
+                        search process after the crash happen
+run.sh               -- run the find_words example
+
+To build the program in this example run: make
+To run it, use the run.sh script.
+
+Modifying the code and run steps is a great way to learn from this example.
+
+In this example we are given a problem to solve:
+In a 2-D matrix of characters (board.txt) we must find all the words from a
+dictionary (dictionary.txt). Words can be formed from the adjecent cells (left,
+right, top, bottom), each cell can be used only once when creating a single
+word.
+
+We will solve this problem, creating trie and performing DFS from every board
+cell, saving current results in on a persistent memory.

examples/I/board.txt

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+metep
+ensrx
+mtisx
+oryxx

examples/I/dictionary.txt

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+persistent memory and nothing else