mention mkdist.sh and summarize the build process in README.md (closes …

…FFTW#85)

README

@@ -43,6 +43,13 @@ re-run configure, you must pass the --enable-maintainer-mode flag:
 
     ./configure --enable-maintainer-mode [OTHER CONFIGURE FLAGS]
 
+Alternatively, you can run
+
+    sh mkdist.sh
+
+which will run the entire bootstrapping process and generate
+.tar.gz files similar to those for official releases.
+
 CONTACTS
 --------
 

README.md

@@ -17,5 +17,10 @@ compiled on any system with a C compiler.
 
 Advanced users and FFTW maintainers can obtain code from github and
 run the generation process themselves.  This is a long process that
-requires special tools.  See README for details.
+requires special tools.  See README for details.  (Summary: in
+addition to the usual Unix developer software, you need [GNU
+autotools](https://en.wikipedia.org/wiki/GNU_Build_System) and
+[OCaml](http://www.ocaml.org/).  Then you can run `sh mkdist.sh`
+to compile FFTW and generate `.tar.gz` files similar to the official
+releases.)