Errata fixes (#45)

* fixes to Rmd from Daniela's errata

Ch08-baggboost-lab.Rmd

@@ -223,7 +223,7 @@ grid.fit(X_train, High_train)
 grid.best_score_
 
 ```
-Let’s take a look at the pruned true.
+Let’s take a look at the pruned tree.
 
 ```{python}
 ax = subplots(figsize=(12, 12))[1]
@@ -509,7 +509,7 @@ np.mean((y_test - y_hat_boost)**2)
 ```
 
 
-In this case, using $\lambda=0.2$ leads to a almost the same test MSE
+In this case, using $\lambda=0.2$ leads to almost the same test MSE
 as when using $\lambda=0.001$.