Modify the hint according to user keymappings

[IndianBoy42]

Is your feature request related to a problem? Please describe.
I want to keep 's' to use leap.nvim in the neogit buffer, so i have made a = Stage (mnemonic add)

Describe the solution you'd like
I want to modify the hint at the top of the neogit buffer to say st[a]ge instead. Maybe also add a few other helpful hints. I think this part can be manual, but the ? popup should also be adjusted to include new mappings (it still says s Stage after the above mapping)

[PriceHiller]

With the current way the keymaps are layed out in Neogit this isn't exactly trivial, but it's not hard. If #604 is ok and merged with vim.tbl_add_reverse_lookup then the solution for the hints at the top of the Neogit status buffer are pretty easy to update.

What might be more difficult to set is the help menu bindings in the Neogit status buffer.

[PriceHiller]

Since #604 got merged, I'll see if I can get around to this tomorrow (ideally).

[PriceHiller]

@CKolkey As a heads up #618 only updates the hint mappings at the top of the buffer, it still does not show the correct keybindings in the help popup.

May want to reopen this or I can create a separate issue for that.

[CKolkey]

Oh, it auto closed since I merged the linked PR. Why don't you make a new issue and we can circle back to it when #601 is merged (assuming conflicts)