Update README.md

Added more details to README.md

Author: xtreme-sameer-vohra

README.md

@@ -1,26 +1,39 @@
-# Instructions
+# Stembuild
 
-If you have a `.vhd` file and a `.patch` file for that VHD, then:
+The stembuild binary is used to build BOSH stemcells for Windows 2012R2 and 2016 v1709 on vSphere. See [here](https://github.com/cloudfoundry-incubator/bosh-windows-stemcell-builder/wiki/Creating-a-vSphere-Stemcell-by-Hand) for instructions to build Windows stemcells for vSphere.
 
-```
-stembuild -vhd my-vhd.vhd -delta patchfile.patch -version 1000.0
-```
+It can convert a prepared .vmdk into a stemcell with the appropriate metadata.
 
-will create a stemcell with version `1000.0` in your current working directory.
+Download the latest stembuild from the [Releases page](https://github.com/pivotal-cf-experimental/stembuild/releases).
+
+## Dependencies
+The VMware 'ovftool' binary must be on your path or Fusion/Workstation must be installed (both include the 'ovftool').
+
+## Create a stemcell from a vmdk
+
+Usage `stembuild-linux [OPTIONS...] [-vmdk FILENAME]
+                                  [-output DIRNAME] [-version STEMCELL_VERSION]
+                                  [-os OS_VERSION]`
 
 Process takes between 10 and 20 minutes. See Progress with `-debug` flag.
 
+## Create a stemcell from a vhd
+
+Usage `stembuild-linux [-output DIRNAME] apply-patch <patch manifest yml>`
+
+will generate a stemcell in the current working directory
+
 Other options available with `stembuild -h`.
 
-# Compilation
+## Compilation
 
 See the [wiki](https://github.com/pivotal-cf-experimental/stembuild/wiki/build-stembuild)
 
-# Testing
+## Testing
 
 Older tests were written using the default testing framework.  However, more recent code
 has been test-driven with Ginkgo.  We recommend that any new code be test-driven using Ginkgo.
 
-# Vendoring
+## Vendoring
 
 Vendoring for this project is done using `dep`.