docs: use descriptive macos headings

docs/index.html

@@ -801,7 +801,7 @@ USE_OSGPLUGIN(<plugin2>)
     Install
     <a href="https://developer.apple.com/xcode/">the latest Xcode</a>
     </p>
-    <h5 id="requirements-macos-method-1">Method 1 - MacPorts</h5>
+    <h5 id="requirements-macos-macports">MacPorts</h5>
     <p>
     Install <a href="https://www.macports.org/">MacPorts</a>,
     then run:
@@ -812,7 +812,7 @@ USE_OSGPLUGIN(&lt;plugin2&gt;)
     gdk-pixbuf2 gnutar gsed intltool libffi libtool \
     openssl p5-xml-parser p7zip pkgconfig scons wget xz</pre>
 
-    <h5 id="requirements-macos-method-2">Method 2 - Rudix</h5>
+    <h5 id="requirements-macos-rudix">Rudix</h5>
     <p>
     Install <a href="http://rudix.org/">Rudix</a>,
     then run:
@@ -827,7 +827,7 @@ USE_OSGPLUGIN(&lt;plugin2&gt;)
     missing on Rudix - please open an issue if you find any.
     </p>
 
-    <h5 id="requirements-macos-method-3">Method 3 - Homebrew</h5>
+    <h5 id="requirements-macos-homebrew">Homebrew</h5>
     <p>
     Install <a href="https://brew.sh/">Homebrew</a>,
     then run: