Meta: expand on style rules in the README

In particular around newlines and naming.

Author: yutakahirano

README.md

@@ -80,6 +80,39 @@ is.
 End tags must be omitted when possible and attribute values must not be quoted (if necessary, use
 double quotes).
 
+Place one newline between paragraphs (including list elements). Place three newlines before `<h2>`,
+and two newlines before other headings. This does not apply when a nested heading follows the parent
+heading.
+
+```html
+<ul>
+ <li><p>Do not place a newline above.
+
+ <li><p>Place a newline above.
+</ul>
+
+<p>Place a newline above.
+
+
+<h3>Place two newlines above.</h3>
+
+<h4>Placing one newline is OK here.</h4>
+
+
+<h4>Place two newlines above.</h4>
+```
+
+Use camel case for variable names and sentence case use spaced names for definitions, algorithms,
+etc.
+
+```html
+<p>A <a for=/>request</a> has an associated
+<dfn export for=request id=concept-request-redirect-mode>redirect mode</dfn>,...
+```
+```html
+<p>Let <var>redirectMode</var> be <var>request</var>'s <a for=request>redirect mode</a>.
+```
+
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