title: Adding multiple legends to ggplot
body: <p>I have following multi-layered plot:</p>
  
  <pre><code>df &lt;- data.frame(number = 1:10, 
                   values = rnorm(10), 
                   decision = factor(rbinom(10,1,.5), levels = c(0,1),
                                     labels=c("No","Yes")),
                   expValues = rnorm(10),
                   bandwidth = runif(10, 0,1))
  
  ggplot(df,aes(x = number, y = values, color=decision)) + aes(group=NA) +
    geom_line(size = 1) + 
    geom_point(size = 3,shape = 16) + 
    geom_smooth(data = df, aes(ymin = values-bandwidth , ymax = values+bandwidth), 
                stat = "identity") +
    geom_point(data=df,
               aes(x=number,y=expValues),shape = "x", size = 5, color = "blue") +
    geom_text(data = data.frame(x = Inf, y = max(df$values), label = "Mean  = 12"), 
              aes(label=label, x =  x, y = y) ,
              hjust = 1, vjust = -0.1, color = "brown", size = 10) +
    geom_hline(yintercept=mean(df$values) ,color="blue", linetype = "dashed") +
    theme(text=element_text(size=20))
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/zGw9Q.png" alt="enter image description here"></p>
  
  <p>I want to add legends for <code>geom_hline</code> and <code>geom_point</code> with shape "x", denoting the for the first it is "Cut Value", for the second "Expected Value". </p>
  
  <p>How can I do that?</p>
  
  <p>Note: I checked <a href="https://stackoverflow.com/questions/18394391/r-custom-legend-for-multiple-layer-ggplot">THIS</a> post and <a href="https://stackoverflow.com/questions/11687739/two-legends-based-on-different-datasets-with-ggplot2">THIS</a> post for possible solutions but cannot figure out how can I do it for especially <code>geom_hline</code>.</p>