docs: add comments to Bookmarked functions

This pr add simple comments in the Bookmarked functions improving its documentation.

Signed-off-by: JGBSouza <joaosouzaaa12@usp.br>

Author: JGBSouza

src/app/screens/bookmarked.rs

@@ -1,34 +1,43 @@
 use crate::lore::patch::Patch;
 
 pub struct BookmarkedPatchsets {
+    /// List of all bookmarked patchsets
     pub bookmarked_patchsets: Vec<Patch>,
+    /// Index of the currently selected patchset
     pub patchset_index: usize,
 }
 
 impl BookmarkedPatchsets {
+    /// Increments `patchset_index` by one, unless the last patchset
+    /// is already selected.
     pub fn select_below_patchset(&mut self) {
         if self.patchset_index + 1 < self.bookmarked_patchsets.len() {
             self.patchset_index += 1;
         }
     }
 
+    /// Decrements `patchset_index` by one, unless the first patchset
+    //  is alredy selected.
     pub fn select_above_patchset(&mut self) {
         self.patchset_index = self.patchset_index.saturating_sub(1);
     }
 
+    /// Get a clone of the actual selected patchset
     pub fn get_selected_patchset(&self) -> Patch {
         self.bookmarked_patchsets
             .get(self.patchset_index)
             .unwrap()
             .clone()
     }
 
+    /// Add a patchset to the list of bookmarks if is not already on the list
     pub fn bookmark_selected_patch(&mut self, patch_to_bookmark: &Patch) {
         if !self.bookmarked_patchsets.contains(patch_to_bookmark) {
             self.bookmarked_patchsets.push(patch_to_bookmark.clone());
         }
     }
 
+    /// Remove a patchset from the list of bookmarks
     pub fn unbookmark_selected_patch(&mut self, patch_to_unbookmark: &Patch) {
         if let Some(index) = self
             .bookmarked_patchsets