ripgrep: disable hyperlinks by default

As a result of discussion in #2611, it seems prudent to disable
hyperlinks by default. Ideally they would be enabled, but it looks like
some environments may barf on them. Since this is the first release with
hyperlink support, it makes sense to me at least to make users opt into
them. This does not preclude enabling them by default in future
releases.

crates/core/app.rs

@@ -1565,10 +1565,12 @@ empty string.
 A format string may be empty. An empty format string is equivalent to the
 'none' alias. In this case, hyperlinks will be disabled.
 
-At present, the default format when ripgrep detects a tty on stdout all systems
-is 'default'. This is an alias that expands to file://{host}{path} on Unix and
-file://{path} on Windows. When stdout is not a tty, then the default format
-behaves as if it were 'none'. That is, hyperlinks are disabled.
+At present, ripgrep does not enable hyperlinks by default. Users must opt into
+them. If you aren't sure what format to use, try 'default'.
+
+When ripgrep detects a tty on stdout then hyperlinks are automatically
+disabled, regardless of the value of this flag. Users can pass '--color always'
+to forcefully emit hyperlinks.
 
 Note that hyperlinks are only written when a path is also in the output
 and colors are enabled. To write hyperlinks without colors, you'll need to

crates/core/args.rs

@@ -1136,7 +1136,7 @@ impl ArgMatches {
             .wsl_prefix(wsl_prefix());
         let fmt: HyperlinkFormat =
             match self.value_of_lossy("hyperlink-format") {
-                None => "default".parse().unwrap(),
+                None => "none".parse().unwrap(),
                 Some(format) => match format.parse() {
                     Ok(format) => format,
                     Err(err) => {