fix: merge shada after VimLeave, #612.

[ayamir]

No description provided.

[ayamir]

I want to make Telescope oldfiles works normally because sometimes Telescope frecency can't record file opened in time. If no further work, I will make this pr ready for review.

[Jint-lzxy]

What I mean in #612 is we should modify 'shada' (the option). In fact, the current issue is previous ShaDa file(s) won't get merged with the ShaDa in memory since we supplied ! (forced):

						    *:wsh* *:wshada* *E137*
:wsh[ada][!] [file]	Write to ShaDa file [file] (default: see above).
			The information in the file is first read in to make
			a merge between old and new info.  When [!] is used,
			the old information is not read first, only the
			internal info is written (also disables safety checks
			described in |shada-error-handling|).  If 'shada' is
			empty, marks for up to 100 files will be written.
			When you get error "E929: All .tmp.X files exist,
			cannot write ShaDa file!" check that no old temp files
			were left behind (e.g.
			~/.local/state/nvim/shada/main.shada.tmp*).

			Note: Executing :wshada will reset all |'quote| marks.

[Jint-lzxy]

@ayamir @fecet Is Telescope oldfiles working properly now?

[fecet]

@ayamir @fecet Is Telescope oldfiles working properly now?

I have set this to "wshada" and everything works fine since that time.