Add some installation instructions

Makefile

@@ -67,6 +67,11 @@ EXES        := \
 CRATES      := \
   $(sort $(filter $(EXES), $(filter-out md5sum true false, $(EXES))))
 
+INSTALL     ?= $(EXES)
+
+INSTALLEES  := \
+  $(filter $(INSTALL),$(filter-out $(DONT_INSTALL),$(EXES)))
+
 # Programs with usable tests
 TEST_PROGS  := \
   cat \
@@ -151,9 +156,9 @@ install: build/uutils
 uninstall:
 	rm -f $(DESTDIR)$(PREFIX)$(BINDIR)/uutils
 else
-install: $(EXES_PATHS)
+install: $(addprefix build/,$(INSTALLEES))
 	mkdir -p $(DESTDIR)$(PREFIX)$(BINDIR)
-	for prog in $(EXES); do \
+	for prog in $(INSTALLEES); do \
 		install build/$$prog $(DESTDIR)$(PREFIX)$(BINDIR)/$(PROG_PREFIX)$$prog; \
 	done
 

README.md

@@ -34,6 +34,45 @@ To build only a few of the available utilities:
 make BUILD='UTILITY_1 UTILITY_2'
 ```
 
+To build the multicall binary (_i.e._ BusyBox-like binary):
+```
+make MULTICALL=1
+```
+
+Installation Instructions
+-------------------------
+
+To install all available utilities:
+```
+make install
+```
+
+To install all but a few of the available utilities:
+```
+make DONT_INSTALL='UTILITY_1 UTILITY_2' install
+```
+
+To install only a few of the available utilities:
+```
+make INSTALL='UTILITY_1 UTILITY_2' install
+```
+
+To install the multicall binary:
+```
+make MULTICALL=1 install
+```
+
+To install every program (other than the multicall binary) with a prefix:
+```
+make PROG_PREFIX=PREFIX_GOES_HERE install
+```
+
+Uninstallation Instructions
+---------------------------
+
+Do the same command as in the Installation Instructions above, but replace
+```install``` with ```uninstall```.
+
 Test Instructions
 -----------------
 
@@ -76,6 +115,7 @@ To do
 - chown
 - chroot
 - copy
+- cp (not much done)
 - cp-hash
 - csplit
 - cut