Add more style guides

Author: jonhiggs

doc/style.md

@@ -3,4 +3,12 @@ bash-my-aws style guide
 
 * Always quote "$variables"
 * Only use parentheses around variables when not surrounded with whitespace (better way to phrase this?)
-* use "$(date)" rather than "`date`"
+* use ``$(date)`` rather than "``date``"
+* use `[[` and `]]` rather than `[`, `]`, or `test`
+
+* show errors with `__bma_error()`
+* show usage options with `__bma_usage()`
+* parse inputs with `__bma_read_inputs()`
+* make sure commands support `--json` and `--text` output options
+
+* regenerate and test the bash_completion script after adding new functions