Add Makefile, README: installation instructions as in the Makefile

Makefile

@@ -0,0 +1,32 @@
+# pipefail is not POSIX complaint
+
+# Export these variables for all commands in this Makefile
+# the 'export' seems not to be necessary
+$(eval isGuix := $(shell command -v guix > /dev/null 2>&1 && echo t || echo f))
+$(eval destDir := $(shell [ "${isGuix}" = t ] && echo $${dotf}/bin || echo ~/bin))
+
+all: show-environment clean install-deps
+	[ ! -d ${destDir} ] && mkdir ${destDir} || :
+	raco exe -o ${destDir}/search-notes main.rkt
+	[ "${isGuix}" = t ] && gxhre --cores=${cores} || :
+
+	@# both can be used: ${...} also $(...)
+	@# commands must be terminated by '; \'
+	@# @if [ "$(isGuix)" = t ]; then \
+	# 	@# echo '# => $$isGuix: ${isGuix}; true branch'; \
+	# else \
+	# 	@# echo '# => $$isGuix: ${isGuix}; false branch'; \
+	# 	: ; \
+	# fi
+
+show-environment:
+	@echo '### => $$isGuix: ${isGuix}'
+	@echo '### => $$destDir: ${destDir}'
+
+install-deps:
+	@# without --skip-installed the this target fails.
+	raco pkg install --skip-installed --auto ansi-color
+
+clean:
+	rm -rf ./compiled/ ./scribblings/compiled/
+

README.md

@@ -1,14 +1,15 @@
 search-notes
 ============
-Installation:
+Installation: run `make`. See also Makefile.
 ```bash
 # Fix the 'loading code: version mismatch' error
 rm -rf ./compiled/ ./scribblings/compiled/
 raco pkg install --auto ansi-color
-command -v guix && destDir=$dotf/bin || destDir=~/bin
-[ ! -d $destDir ] && mkdir $destDir
+isGuix=$(command -v guix > /dev/null 2>&1 && echo t || echo f)
+[ ${isGuix} = t ] && destDir=$dotf/bin || destDir=~/bin
+[ ! -d ${destDir} ] && mkdir $destDir || :
 raco exe -o $destDir/search-notes main.rkt
-# gxhre --cores=24
+[ ${isGuix} = t ] && gxhre --cores=${cores} || :
 ```
 
 See main.rkt -> command-line -> #:usage-help