Auto merge of #212 - servo:docs, r=KiChjang

Add more doc examples.

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src/lib.rs

@@ -423,6 +423,15 @@ impl Url {
     }
 
     /// Return the scheme of this URL, lower-cased, as an ASCII string without the ':' delimiter.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use url::Url;
+    ///
+    /// let url = Url::parse("file:///tmp/foo").unwrap();
+    /// assert_eq!(url.scheme(), "file");
+    /// ```
     #[inline]
     pub fn scheme(&self) -> &str {
         self.slice(..self.scheme_end)
@@ -460,6 +469,9 @@ impl Url {
     /// let url = Url::parse("ftp://rms@example.com").unwrap();
     /// assert_eq!(url.username(), "rms");
     ///
+    /// let url = Url::parse("ftp://:secret123@example.com").unwrap();
+    /// assert_eq!(url.username(), "");
+    ///
     /// let url = Url::parse("https://example.com").unwrap();
     /// assert_eq!(url.username(), "");
     /// ```
@@ -472,6 +484,24 @@ impl Url {
     }
 
     /// Return the password for this URL, if any, as a percent-encoded ASCII string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use url::Url;
+    ///
+    /// let url = Url::parse("ftp://rms:secret123@example.com").unwrap();
+    /// assert_eq!(url.password(), Some("secret123"));
+    ///
+    /// let url = Url::parse("ftp://:secret123@example.com").unwrap();
+    /// assert_eq!(url.password(), Some("secret123"));
+    ///
+    /// let url = Url::parse("ftp://rms@example.com").unwrap();
+    /// assert_eq!(url.password(), None);
+    ///
+    /// let url = Url::parse("https://example.com").unwrap();
+    /// assert_eq!(url.password(), None);
+    /// ```
     pub fn password(&self) -> Option<&str> {
         // This ':' is not the one marking a port number since a host can not be empty.
         // (Except for file: URLs, which do not have port numbers.)