Update cheatsheets

linux/goobook

@@ -0,0 +1,17 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# goobook
+
+> Access Google contacts from `mutt` or the command-line.
+> More information: <https://manned.org/goobook>.
+
+- Allow `goobook` to access Google contacts using OAuth2:
+
+`goobook authenticate`
+
+- Dump all contacts to XML (`stdout`):
+
+`goobook dump_contacts`