Remove --max-gain CLI option from docs

The option didn't make sense as max-gain is the default state, so it's
already on unless you use the --gain option.

Author: watson

README.md

@@ -82,7 +82,6 @@ The following options are available when running `airplanejs`:
 - `--device <index>` - Select RTL dongle (alias: `-d`, default: `0`)
 - `--frequency <hz>` - Set custom frequency (alias: `-f`, default: `1090000000`)
 - `--gain <gain>` - Set custom tuner gain (alias: `-g`)
-- `--max-gain` - Set tuner gain to highest possible value (default: on)
 - `--auto-gain` - Disable manual tuner gain (default: off)
 - `--enable-agc` - Use Automatic Gain Control (default: off)
 - `--port <port>` - Set custom HTTP server port (alias: `-p`, default: `3000`)

server.js

@@ -204,7 +204,6 @@ function help () {
   console.log('  --device -d <index>  Select RTL dongle (default: 0)')
   console.log('  --frequency -f <hz>  Set custom frequency (default: 1090000000)')
   console.log('  --gain -g <gain>     Set custom tuner gain')
-  console.log('  --max-gain           Set tuner gain to highest possible value (default: on)')
   console.log('  --auto-gain          Disable manual tuner gain (default: off)')
   console.log('  --enable-agc         Use Automatic Gain Control (default: off)')
   console.log('  --port -p <port>     Set custom HTTP server port (default: 3000)')