add docs here, not wiki; overview, install via package manager

README.md

@@ -3,3 +3,19 @@ cloc counts blank lines, comment lines, and physical lines of source code in man
 
 Originally hosted at http://cloc.sourceforge.net/, cloc began the transition to github in
 September 2015.
+
+# Overview
+
+cloc counts blank lines, comment lines, and physical lines of source code in many programming languages. Given two versions of a code base, cloc can compute differences in blank, comment, and source lines. It is written entirely in Perl with no dependencies outside the standard distribution of Perl v5.6 and higher (code from some external modules is embedded within cloc) and so is quite portable. cloc is known to run on many flavors of Linux, FreeBSD, NetBSD, OpenBSD, Mac OS X, AIX, HP-UX, Solaris, IRIX, z/OS, and Windows. (To run the Perl source version of cloc on Windows one needs ActiveState Perl 5.6.1 or higher, Strawberry Perl, Cygwin, or MobaXTerm with the Perl plug-in installed. Alternatively one can use the Windows binary of cloc generated with PAR::Packer to run on Windows computers that have neither Perl nor Cygwin.)
+
+cloc contains code from David Wheeler's SLOCCount, Damian Conway and Abigail's Perl module Regexp::Common, Sean M. Burke's Perl module Win32::Autoglob, and Tye McQueen's Perl module Algorithm::Diff. Language scale factors were derived from Mayes Consulting, LLC web site http://softwareestimator.com/IndustryData2.htm.
+
+## Install via package manager
+Depending your operating system, one of these installation methods may work for you:
+
+    npm install -g cloc                    # https://www.npmjs.com/package/cloc
+    sudo apt-get install cloc              # Debian, Ubuntu
+    sudo yum install cloc                  # Red Hat, Fedora
+    sudo pacman -S cloc                    # Arch
+    sudo pkg install cloc                  # FreeBSD
+    sudo port install cloc                 # Mac OS X with MacPorts