Make negative adverbs above snippets bold

Increase legibility of negative sentences in counter examples.

Closes #1503

Author: felicio

docs/rules/boolean-prop-naming.md

@@ -15,7 +15,7 @@ var Hello = createReactClass({
 });
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 var Hello = createReactClass({
@@ -64,4 +64,4 @@ For supporting "is" naming:
 
 ```jsx
 "react/boolean-prop-naming": ["error", { "rule": "^is[A-Z]([A-Za-z0-9]?)+" }]
-```
+```

docs/rules/default-props-match-prop-types.md

@@ -98,7 +98,7 @@ MyStatelessComponent.defaultProps = {
 }
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 function MyStatelessComponent({ foo, bar }) {

docs/rules/display-name.md

@@ -14,7 +14,7 @@ var Hello = createReactClass({
 });
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 var Hello = createReactClass({
@@ -37,7 +37,7 @@ var Hello = createReactClass({
 
 When `true` the rule will ignore the name set by the transpiler and require a `displayName` property in this case.
 
-The following patterns are considered okay and do not cause warnings:
+The following patterns are considered okay and do **not** cause warnings:
 
 ```jsx
 var Hello = createReactClass({

docs/rules/forbid-component-props.md

@@ -17,7 +17,7 @@ The following patterns are considered warnings:
 <Hello style={{color: 'red'}} />
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 <Hello name='Joe' />

docs/rules/forbid-elements.md

@@ -23,7 +23,7 @@ An array of strings and/or objects. An object in this array may have the followi
 
 A string item in the array is a shorthand for `{ element: string }`.
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 // [1, { "forbid": ["button"] }]

docs/rules/forbid-foreign-prop-types.md

@@ -19,7 +19,7 @@ var { propTypes } = SomeComponent;
 SomeComponent['propTypes'];
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```js
 import SomeComponent, {propTypes as someComponentPropTypes} from './SomeComponent';

docs/rules/jsx-boolean-value.md

@@ -16,7 +16,7 @@ The following patterns are considered warnings when configured `"never"`, or wit
 var Hello = <Hello personal={true} />;
 ```
 
-The following patterns are not considered warnings when configured `"never"`, or with `"always", { "never": ["personal"] }`:
+The following patterns are **not** considered warnings when configured `"never"`, or with `"always", { "never": ["personal"] }`:
 
 ```jsx
 var Hello = <Hello personal />;
@@ -28,7 +28,7 @@ The following patterns are considered warnings when configured `"always"`, or wi
 var Hello = <Hello personal />;
 ```
 
-The following patterns are not considered warnings when configured `"always"`, or with `"never", { "always": ["personal"] }`:
+The following patterns are **not** considered warnings when configured `"always"`, or with `"never", { "always": ["personal"] }`:
 
 ```jsx
 var Hello = <Hello personal={true} />;

docs/rules/jsx-closing-bracket-location.md

@@ -21,7 +21,7 @@ The following patterns are considered warnings:
   />;
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 <Hello firstName="John" lastName="Smith" />;
@@ -138,7 +138,7 @@ var x = function() {
 </Say>;
 ```
 
-The following patterns are not considered warnings:
+The following patterns are **not** considered warnings:
 
 ```jsx
 // 'jsx-closing-bracket-location': 1

docs/rules/jsx-closing-tag-location.md

@@ -21,7 +21,7 @@ The following patterns are considered warnings:
   marklar</Hello>
 ```
 
-The following are not considered warnings:
+The following are **not** considered warnings:
 
 ```jsx
 <Hello>

docs/rules/jsx-curly-brace-presence.md

@@ -139,7 +139,7 @@ will warned and fixed to:
 
 * If the rule is set to get rid of unnecessary curly braces(JSX expression) and there are characters that need to be escaped in its JSX form, such as quote characters, [forbidden JSX text characters](https://facebook.github.io/jsx/), escaped characters and anything that looks like HTML entity names, the code will not be warned because the fix may make the code less readable.
 
-The following pattern will not be given a warning even if `'never'` is passed.
+The following pattern will **not** be given a warning even if `'never'` is passed.
 
 ```jsx
 <Color text={"\u00a0"} />