chore(keymap): remove "<space>E"

- Personally, I never uses this shortcut
- Secondly, we are running out of keys for mappings, so I would like to
  reserve "<space>E" for other more useful mappings

book/src/keymap.md

@@ -292,7 +292,6 @@ This layer is a kludge of mappings, mostly pickers.
 | `/`     | Global search in workspace folder                                       | `global_search`                            |
 | `?`     | Open command palette                                                    | `command_palette`                          |
 | `e`     | Reveal current file in explorer                                         | `reveal_current_file`                      |
-| `E`     | Open or focus explorer                                                  | `toggle_or_focus_explorer`                 |
 
 
 > 💡 Global search displays results in a fuzzy picker, use `Space + '` to bring it back up after opening a file.

helix-term/src/keymap/default.rs

@@ -275,7 +275,6 @@ pub fn default() -> HashMap<Mode, Keymap> {
             "h" => select_references_to_symbol_under_cursor,
             "?" => command_palette,
             "e" => reveal_current_file,
-            "E" => open_or_focus_explorer,
         },
         "z" => { "View"
             "z" | "c" => align_view_center,