* initial style guide prototype with examples

* clarify component style scoping in 3rd-party libs

* flesh out rule for complex computed properties

* clarify component style scoping

* flesh out self-closing components rule in style guide

* flesh out style guide entry for component name casing in JS/JSX

* complete draft for priority A rules

* complete draft for priority B rules

* style guide fixes after @KatieMFritz's review

* fix code block styles, especially on style guide

* fix wrong formatting for in-dom templates style rule

* simplify data function detailed explanation in style guide

* in style guide, add detailed explanation with example for keyed v-for

* in style guide, improve explanation of order of words in component names

* in style guide, link to SFC and JSX explanations

* WIP

* complete definitions for all style guide rules

* minor language tweaks to style guide

* update SG recommendation for nested component directories, courtesy of @Akryum

* fix SG typo in self-closing components example

* update SG component options order, tag @Akryum @posva

* add category tags to rule titles

* style guide round of edits and simplification

* move list rendering above conditionals in SG element attribute order

* add SG rule about empty lines in component/instance options

* fixed missing and added commas in SG example

* move style guide to its own page

* make exception to multi-word component names for App in SG

* add beta tag to style guide

* fix typos pointed out by @phanan

* clarify keyed v-for rule in SG

* update when component subdirectories are worth considering in SG

* add link to HTML spec in multi-word component names SG rule