support @receiver KDoc tag; somewhat more precise tag name completion

idea/testData/editor/quickDoc/OnMethodUsageWithReceiver.kt

@@ -0,0 +1,19 @@
+/**
+Some documentation
+
+ * @receiver Some int
+ * @param b String
+ * @return Return [a] and nothing else
+ */
+fun Int.testMethod(b: String) {
+
+}
+
+fun test() {
+    1.<caret>testMethod("value")
+}
+
+//INFO: <b>public</b> <b>fun</b> Int.testMethod(b: String): Unit <i>defined in</i> root package<p>Some documentation</p>
+//INFO: <dl><dt><b>Receiver:</b></dt><dd>Some int</dd></dl>
+//INFO: <dl><dt><b>Parameters:</b></dt><dd><code>b</code> - String</dd></dl>
+//INFO: <dl><dt><b>Returns:</b></dt><dd>Return <a href="psi_element://a">a</a> and nothing else</dd></dl>