docs: Fix typos (#398)

src/handler.rs

@@ -89,7 +89,7 @@ impl MietteHandlerOpts {
     /// Syntax highlighting is disabled by default unless the
     /// `syntect-highlighter` feature is enabled. Call this method
     /// to override the default and use a custom highlighter
-    /// implmentation instead.
+    /// implementation instead.
     ///
     /// Use
     /// [`without_syntax_highlighting()`](MietteHandlerOpts::without_syntax_highlighting())

src/handlers/graphical.rs

@@ -799,7 +799,7 @@ impl GraphicalReportHandler {
             return Ok(());
         }
 
-        // keeps track of how many colums wide the gutter is
+        // keeps track of how many columns wide the gutter is
         // important for ansi since simply measuring the size of the final string
         // gives the wrong result when the string contains ansi codes.
         let mut gutter_cols = 0;