General mention of man and help.

README.md

@@ -42,6 +42,8 @@ Notes:
 
 - Learn at least one text-based editor well. Ideally Vim (`vi`), as there's really no competition for random editing in a terminal (even if you use Emacs, a big IDE, or a modern hipster editor most of the time).
 
+- Know how to read documentation with `man` (for the inquisitive, `man man` lists the section numbers, e.g. 1 is "regular" commands, 5 is files/conventions, and 8 are for administration). Know that some commands are not executables, but Bash builtins, and that you can get help on them with `help` and `help -d`.
+
 - Learn about redirection of output and input using `>` and `<` and pipes using `|`. Learn about stdout and stderr.
 
 - Learn about file glob expansion with `*` (and perhaps `?` and `{`...`}`) and quoting and the difference between double `"` and single `'` quotes. (See more on variable expansion below.)