support search history?

[v6cc]

hope support use <c-n> <c-p> in insert mode to get history search

[RishabhRD]

Not sure about it. It means the plugin has to maintain an array of old search
entries. And its size would increase with every usage of the plugin. I am just
thinking can we utilize some vim/neovim capability here so that we don't have
to use the list. Do you have any vim/neovim feature in mind that can help us
to implement this with O(1) memory usage?

[v6cc]

@RishabhRD May be just maintain recent 10 search history? too many seems not useful

[RishabhRD]

@zdmgmail maintaining 10 in search history would be a sort of hack. However, if
done using a command also, like vimscript command, it would maintain history.
So, we can't escape from memory usage. Hence, I thought we can maintain it
ourselves to get more control.

Just update popfix and nvim-cheat.sh to get the feature. 😃

I have updated readme for the new mappings.

Thanks for such a valuable suggestion.