improve install instructions for pg_golden_axe

Author: ryansmith3136

pg_golden_axe/readme.md

@@ -0,0 +1,17 @@
+## Mac Development
+
+```
+brew install git icu4c pkg-config
+export PKG_CONFIG_PATH=/opt/homebrew/opt/icu4c/lib/pkgconfig
+cargo pgrx init --pg18 download
+
+cargo test -p be #expect failures
+cargo pgrx install -p pg_golden_axe -c /tmp/golden-axe-pg-test/install/postgresql-18.1.0-aarch64-apple-darwin/bin/pg_config
+```
+
+
+## Server Deployment
+
+```
+sudo apt-get install clang build-essential libreadline-dev zlib1g-dev flex bison libxml2-dev libxslt-dev libssl-dev libxml2-utils xsltproc ccache pkg-config
+```