Update documentation to warn about Ruby 2.7.0 and 2.7.1. ruby-prof/ruby-prof#279.

Author: cfis

index.html

@@ -88,9 +88,13 @@ <h2><a id="installation">Installation</a></h2>
           are running Windows, then you should install the Windows specific gem
           or install install <a href="https://rubyinstaller.org/add-ons/devkit.html">devkit</a>.</p>
         <p>ruby-prof requires Ruby 2.4.0 or higher.</p>
-        <p><strong>!!!WARNING!!!</strong> - The TracePoint api in Ruby versions
-          2.6.1 through 2.6.3 has a <a href="https://bugs.ruby-lang.org/issues/15911">bug</a>
+        <p><strong>!!!WARNING!!!</strong></p>
+        <p>Ruby versions 2.6.1, 2.6.2 and 2.6.3 have a <a href="https://bugs.ruby-lang.org/issues/15911">bug</a>
           that can cause ruby-prof to return incorrect results. </p>
+        <p>Ruby versions 2.7.0 and 2.7.1 have a <a href="https://bugs.ruby-lang.org/issues/17152">bug</a>
+          that can cause ruby-prof to return incorrect results.</p>
+        <p><br>
+        </p>
         <h2><a id="getting-started">Getting Started</a></h2>
         <p>There are three ways to use ruby-prof:</p>
         <ul>