Fix invalid HTML tag warnings in generated docs

Several documentation items were enclosed in angle brackets, which
would cause rustdoc to interpret them as HTML tags, generating
incorrect documentation. Enclose these in backticks for clarity.
While we are at it, fix list formatting for said items.

See-also: https://doc.rust-lang.org/rustdoc/lints.html#invalid_html_tags
Signed-off-by: Carlos López <carlos.lopez@suse.com>

Author: 00xc

src/cmdline/mod.rs

@@ -433,12 +433,14 @@ impl Cmdline {
         slug.matches('\"').count() % 2 == 0
     }
 
-    /// Tries to build a [`Cmdline`] with a given capacity from a str. The format of the
-    /// str provided must be one of the followings:
-    /// -> <boot args> -- <init args>
-    /// -> <boot args>
-    /// where <boot args> and <init args> can contain '--' only if double quoted and
-    /// <boot args> and <init args> contain at least one non-whitespace char each.
+    /// Tries to build a [`Cmdline`] with a given capacity from a [`str`]. The format of the
+    /// str provided must be one of the following:
+    ///
+    /// * `<boot args> -- <init args>`
+    /// * `<boot args>`
+    ///
+    /// where `<boot args>` and `<init args>` can contain `--` only if double quoted and
+    /// `<boot args>` and `<init args>` contain at least one non-whitespace char each.
     ///
     /// Providing a str not following these rules might end up in undefined behaviour of
     /// the resulting `Cmdline`.