Update README and help

README.md

@@ -63,4 +63,5 @@ screen, touch the help icon.
 The input source may be selected. Some of the selections will not be
 available, depending on the device. The fill option selects spectrum
 trace fill. The screen option will stop the screen turning off. The
-about item shows the version and copyright.
+theme option selects the dark theme. The about item shows the version
+and copyright.

src/main/res/raw/help.html

@@ -48,13 +48,15 @@ <h3>Spectrum</h3>
 
 <p>The spectrum display shows a spectrum with a logarithmic frequency
 scale. An index line shows the dominant frequency in the input. The
-frequency is also displayed in the toolbar. To lock the display, touch
-spectrum display or the lock icon in the toolbar. Touch it again to
-release the lock. To display the help screen, touch the help icon.</p>
+frequency and input level is also displayed in the toolbar. To lock
+the display, touch spectrum the display or the lock icon in the
+toolbar. Touch it again to release the lock. To display the help
+screen, touch the help icon.</p>
 
 <h3>Settings</h3>
 
 <p>The input source may be selected. Some of the selections will not
 be available, depending on the device. The fill option selects
 spectrum trace fill. The screen option will stop the screen turning
-off. The about item shows the version and copyright.</p>
+off. The theme option selects the dark theme. The about item shows the
+version and copyright.</p>