Generic/OpeningFunctionBraceKernighanRitchie: improve XML documentation (#927)

* Generic/OpeningFunctionBraceKernighanRitchie: fix syntax errors in the XML doc code examples

* Generic/OpeningFunctionBraceKernighanRitchie: improve XML doc

- `<documentation>` title matches the sniff name.
- Don't mention the Kernighan/Ritchie style in the `<standard>`
description as according to Wikipedia this style uses the opening brace
for functions on a separate line and not on the same line (https://en
.wikipedia.org/wiki/Indentation_style#K&R).
- I believe it is more precise to say that the sniff checks if the
opening brace is on the same line as the closing parenthesis and not the
function declaration as the function declaration can be multi-line.
- Mention in the `<standard>` description that there must be no content
on the line after the opening brace.
- Improve the title of the `<code>` blocks.

Author: rodrigoprimo

src/Standards/Generic/Docs/Functions/OpeningFunctionBraceKernighanRitchieStandard.xml

@@ -1,22 +1,24 @@
-<documentation title="Opening Brace in Function Declarations">
+<documentation title="Opening Function Brace Kerninghan Ritchie">
     <standard>
     <![CDATA[
-    Function declarations follow the "Kernighan/Ritchie style". The function brace is on the same line as the function declaration. One space is required between the closing parenthesis and the brace.
+    The function opening brace must be on the same line as the end of the function declaration, with
+    exactly one space between the end of the declaration and the brace. The brace must be the last
+    content on the line.
     ]]>
     </standard>
     <code_comparison>
-        <code title="Valid: Brace on same line.">
+        <code title="Valid: Opening brace on the same line.">
         <![CDATA[
 function fooFunction($arg1, $arg2 = '')<em> {</em>
-    ...
+    // Do something.
 }
         ]]>
         </code>
-        <code title="Invalid: Brace on next line.">
+        <code title="Invalid: Opening brace on the next line.">
         <![CDATA[
 function fooFunction($arg1, $arg2 = '')
 <em>{</em>
-    ...
+    // Do something.
 }
         ]]>
         </code>