Updated README.md with more complete instructions that will show up on the github page.

diff --git a/README.md b/README.md
index 759e699..310dc7d 100644
--- a/README.md
+++ b/README.md

@@ -38,9 +38,30 @@
 
 Instructions:
 
-There is a top-level Makefile but generally it is recommended to cd
-to the directory for the target foundry process and follow the instructions
-in the README file there (e.g., sky130/README).
+    git clone https://github.com/RTimothyEdwards/open_pdks.git
+    cd open_pdks
+    ./configure [options]
+    make
+    make install
 
-Also see the website at http://opencircuitdesign.com/open_pdks
+where the configure [options] are specific to each foundry PDK supported
+by open_pdks and can be queried using
+
+    ./configure --help
+
+At a minimum you will want to pass a configure option to declare the location
+of the PDK vendor source distribution (which can be obtained separately),
+
+    ./configure --with-[PDK_name]-source=[path]
+
+The open_pdks version of the PDK can be built locally within open_pdks without
+the need to declare an install target or run "make install".  However, it is
+recommended to declare a target location and install there, using
+
+    ./configure --with-[PDK_name]-source=[path] --with-[PDK_name]-local-path=[path]
+
+followed by "make" and "make install".
+
+Also see the website at http://opencircuitdesign.com/open_pdks/.  The "Install"
+page has full instructions for configuring and installing open_pdks.