Add 2004/sds/try.sh + format/typo checks

The try.sh script runs what used to be in the try section.

Format/typo fix README.md in full. This commit also fixes an
inconsistency where the author unwittingly used the word stenography
instead of steganography, a very easy mistake to make and one that I
almost missed.

Updated Makefile to silence a couple warnings.

Updated .gitignore.

2004/sds/try.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+#
+# try.sh - demonstrate IOCCC winner 2004/sds
+#
+
+# make sure CC is set so that when we do make CC="$CC" it isn't empty. Doing it
+# this way allows us to have the user specify a different compiler in an easy
+# way.
+if [[ -z "$CC" ]]; then
+    CC="cc"
+fi
+
+make CC="$CC" all >/dev/null || exit 1
+
+# clear screen after compilation so that only the entry is shown
+clear
+
+echo "$ ./sds < sds.c > encoder.c" 1>&2
+./sds < sds.c > encoder.c
+echo 1>&2
+
+echo "$ make encoder 2>/dev/null" 1>&2
+make encoder 2>/dev/null
+echo 1>&2
+
+echo "$ ./encoder README.md <sds.c >sds_msg.c"
+./encoder README.md <sds.c >sds_msg.c
+
+echo "$ make sds_msg 2>/dev/null" 1>&2
+make sds_msg 2>/dev/null
+echo 1>&2
+
+echo "$ ./sds_msg < sds.c > sds2_msg.c" 1>&2
+./sds_msg < sds.c > sds2_msg.c
+
+echo "$ diff sds2_msg.c encoder.c" 1>&2
+diff sds2_msg.c encoder.c
+
+echo "$ echo 'Hello, World!' > message" 1>&2
+echo 'Hello, World!' > message
+
+echo "$ ./encoder message < README.md > remarks.md" 1>&2
+./encoder message < README.md > remarks.md
+
+read -r -n 1 -p "Press any key to show diff remarks.md README.md: "
+echo "$ diff remarks.md README.md" 1>&2
+diff remarks.md README.md # notice how similar they are
+echo "Did you notice how similar they are?" 1>&2
+echo 1>&2
+read -r -n 1 -p "Press any key to continue: "
+
+echo 1>&2
+# and then observe:
+echo "$ ./sds < remarks.md" 1>&2
+./sds < remarks.md