Be more explicit with our versions

netlify.toml

@@ -2,4 +2,17 @@
   # Directory (relative to root of your repo) that contains the deploy-ready 
   # HTML files and assets generated by the build. If a base directory has
   # been specified, include it in the publish directory path.
-  publish = "docs/latest/_book/"
+  publish = "docs/latest/_book/"
+
+# COMMENT: NODE_VERSION in root `.nvmrc` takes priority
+# COMMENT: Why we specify YARN_FLAGS: https://www.netlify.com/docs/build-gotchas/#yarn
+[build.environment]
+  NODE_VERSION = "10.15.3"
+  YARN_VERSION = "1.15.2"
+  YARN_FLAGS = "--no-ignore-optional --pure-lockfile"
+
+# COMMENT: This a rule for Single Page Applications
+[[redirects]]
+  from = "/*"
+  to = "/index.html"
+  status = 200