Write down stylistic things we should be doing throughout

So that we can make sure we're consistent.

style-guide.md

@@ -0,0 +1,34 @@
+# Style Guide
+
+## Prose
+
+* Prefer title case for chapter/section headings, ex: `## Generating a Secret
+  Number` rather than `## Generating a secret number`.
+* Prefer italics over single quotes when calling out a term, ex: `is an
+  *associated function* of` rather than `is an ‘associated function’ of`.
+* When talking about a method in prose, include the parentheses, ex:
+  `read_line()` rather than `read_line`.
+* Hard wrap at 80 chars
+* Prefer not mixing code and not-code in one word, ex: ``Remember when we wrote
+  `use std::io`?`` rather than ``Remember when we `use`d `std::io`?``
+
+## Code
+
+* Add the file name before markdown blocks to make it clear which file we're
+  talking about, when applicable.
+* When making changes to code, make it clear which parts of the code changed
+  and which stayed the same... not sure how to do this yet
+* Split up long lines as appropriate to keep them under 80 chars if possible
+* Use `bash` syntax highlighting for command line output code blocks
+
+## Links
+
+Once all the scripts are done:
+
+* If a link shouldn't be printed, mark it to be ignored
+  * This includes all "Chapter XX" intra-book links, which *should* be links
+    for the HTML version
+* Make intra-book links and stdlib API doc links relative so they work whether
+  the book is read offline or on docs.rust-lang.org
+* Use markdown links and keep in mind that they will be changed into `text at
+  *url*` in print, so word them in a way that it reads well in that format