Merge pull request #499 from smallstep/carl/readmes

Update "build from source" instructions

README.md

@@ -108,6 +108,8 @@ ACME is the protocol used by Let's Encrypt to automate the issuance of HTTPS cer
 These instructions will install an OS specific version of the `step-ca` binary on
 your local machine.
 
+Want to build from source? See [our contributor's guide](./docs/CONTRIBUTING.md)
+
 ### Mac OS
 
 Install `step`  and `step-ca` together, via [Homebrew](https://brew.sh/):

docs/CONTRIBUTING.md

@@ -16,18 +16,64 @@ to manage issues, etc.
 
 ## Building From Source
 
+Clone this repository to get a bleeding-edge build, 
+or download the source archive for [the latest stable release](https://github.com/smallstep/certificates/releases/latest).
+
+### Build a standard `step-ca`
+
 The only prerequisites are [`go`](https://golang.org/) and make.
 
 To build from source:
 
     make bootstrap && make
 
+Find your binaries in `bin/`.
+
+### Build `step-ca` using CGO
+
+#### The CGO build enables PKCS #11 and YubiKey PIV support
+
+To build the CGO version of `step-ca`, you will need [`go`](https://golang.org/), make, and a C compiler.
+
+You'll also need PCSC support on your operating system, as required by the `go-piv` module.
+On Linux, the [`libpcsclite-dev`](https://pcsclite.apdu.fr/) package provides PCSC support.
+On macOS and Windows, PCSC support is built into the OS.
+
+#### 1. Install PCSC support
+
+On Debian-based distributions, run:
+
+```shell
+sudo apt-get install libpcsclite-dev
+```
+
+On Fedora:
+
+```shell
+sudo yum install pcsc-lite-devel
+```
+
+On CentOS:
+
+```
+sudo yum install 'dnf-command(config-manager)'
+sudo yum config-manager --set-enabled PowerTools
+sudo yum install pcsc-lite-devel
+```
+
+#### 2. Build `step-ca`
+
+To build `step-ca`, clone this repository and run the following:
+
+```shell
+make bootstrap && make build GOFLAGS=""
+```
+
+When the build is complete, you will find binaries in `bin/`.
 
 ## Asking Support Questions
 
-Users and developers can ask questions over email (info@smallstep.com) or
+Feel free to post a question on our [GitHub Discussions](https://github.com/smallstep/certificates/discussions) page, or find us on [Gitter](https://gitter.im/smallstep/community).
-[twitter](https://twitter.com/smallsteplabs). Please don't use the GitHub
-issue tracker to ask questions.
 
 ## Reporting Issues