env/darwin/macstadium: update image documentation

The macOS Catalina builder release requires additional notes
to be added to the macOS builder documentation.

Change-Id: I181c0175b46e0359ba940107311dda9a31dfdd68
Reviewed-on: https://go-review.googlesource.com/c/build/+/226841
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/env/darwin/macstadium/README.md b/env/darwin/macstadium/README.md
index f2951bc..1d53c8d 100644
--- a/env/darwin/macstadium/README.md
+++ b/env/darwin/macstadium/README.md
@@ -14,7 +14,7 @@
 
     $ ssh -i ~/keys/id_ed25519_golang1 gopher@macstadiumd.golang.org
 
-(Where `id_ed255519_golang` is available from http://go/go-builders-ssh)
+(Where `id_ed255519_golang1` is available from http://go/go-builders-ssh)
 
 It also runs:
 
@@ -57,6 +57,20 @@
 (Alternatively, `ssh -D` to the bastion host to make a SOCKS tunnel
 and configure your browser to send proxy through that SOCKS tunnel.)
 
+## Adding a New Image
+
+When a new version of macOS is released:
+
+* Ensure that the version of vSphere deployed on MacStadium supports the
+  new version of macOS. If it doesn't, either request that MacStadium
+  upgrade the cluster or seek guidance from them about the upgrade path.
+
+* Clone the latest macOS version on vSphere and upgrade that version
+  to the desired macOS version as per the [instructions](vmware-notes.md).
+
+* If a completely new image is required, follow the [images setup notes](image-setup-notes.txt)
+  in order to add a new image.
+
 ## Debugging
 
 Common techniques to debug:
diff --git a/env/darwin/macstadium/image-setup-notes.txt b/env/darwin/macstadium/image-setup-notes.txt
index 0db6946..d0ddb9d 100644
--- a/env/darwin/macstadium/image-setup-notes.txt
+++ b/env/darwin/macstadium/image-setup-notes.txt
@@ -1,3 +1,5 @@
+The Disk should be formatted with a case insensitive file system (default).
+
 Install VMWare tools daemon.
 
   - you should be able to do this from the vSphere UI, but I got errors with Mojave.
@@ -10,7 +12,11 @@
     $ /Library/Application Support/VMware Tools/vmware-tools-daemon --cmd "info-get guestinfo.name"
     No value value
 
-Add $HOME/go1.4
+Download Go 1.13.4 or newer tarball via curl (bootstrap version of Go must be signed and notorized in macOS version >= 10.15).
+
+tar -xf <go.darwin-amd64.tar.gz>
+
+mv go $HOME/goboot
 
 System Preferences > Software Update > off
 
@@ -18,12 +24,14 @@
 
 System Preferences > Energy Saver > never sleep
 
-System Preferences > Sharing > enable ssh (for later)
+System Preferences > Sharing > enable ssh (enable for administrators)
 
 Create executable $HOME/stage0.sh with:
 
    #!/bin/bash
-   while true; do (curl -v http://10.50.0.2:8713/stage0/$(sw_ver -productVersion) | sh); sleep 5; done
+   while true; do (curl -v http://10.50.0.2:8713/stage0/$(sw_vers -productVersion) | sh); sleep 5; done
+
+chmod +x $HOME/stage0.sh
 
 Automator:
 
@@ -43,12 +51,12 @@
     %admin ALL=(ALL) NOPASSWD: ALL
 
 install xcode
-  (as of 10.10 or 10.9, running git first time will propt for install;
-   before that, need to find old xcode version)
+  - Version < 10.9: search and install an older compatible version of Xcode.
+  - Versions 10.10, 10.9: running git first time will prompt for install.
+  - Version => 10.15: download Xcode from the Apple Developer site.
 
 verbose boot: (text instead of apple image)
 
     sudo nvram boot-args="-v"
 
 run-builder-darwin-10_11.sh
-