Option to prioritize file name matches (#4192)

* 'pathname' is a new tiebreak option for prioritizing matches occurring
  in the file name of the path.

* `--scheme=path` will automatically set `--tiebreak=pathname,length`.

* fzf will automatically choose `path` scheme when the input is a TTY device,
  where fzf would start its built-in walker or run `$FZF_DEFAULT_COMMAND`
  which is usually a command for listing files.

Close #4191

README.md

@@ -83,6 +83,7 @@ Table of Contents
     * [Custom fuzzy completion](#custom-fuzzy-completion)
 * [Vim plugin](#vim-plugin)
 * [Advanced topics](#advanced-topics)
+    * [Customizing for different types of input](#customizing-for-different-types-of-input)
     * [Performance](#performance)
     * [Executing external programs](#executing-external-programs)
     * [Turning into a different process](#turning-into-a-different-process)
@@ -718,6 +719,22 @@ See [README-VIM.md](README-VIM.md).
 Advanced topics
 ---------------
 
+### Customizing for different types of input
+
+Since fzf is a general-purpose text filter, its algorithm was designed to
+"generally" work well with any kind of input. However, admittedly, there is no
+true one-size-fits-all solution, and you may want to tweak the algorithm and
+some of the settings depending on the type of the input. To make this process
+easier, fzf provides a set of "scheme"s for some common input types.
+
+| Scheme             | Description                                                                         |
+| :---               | :---                                                                                |
+| `--scheme=default` | Generic scheme designed to work well with any kind of input                         |
+| `--scheme=path`    | Suitable for file paths                                                             |
+| `--scheme=history` | Suitable for command history or any input where chronological ordering is important |
+
+(See `fzf --man` for the details)
+
 ### Performance
 
 fzf is fast. Performance should not be a problem in most use cases. However,
@@ -727,6 +744,8 @@ you might want to be aware of the options that can affect performance.
   makes the initial scanning slower. So it's not recommended that you add it
   to your `$FZF_DEFAULT_OPTS`.
 - `--nth` makes fzf slower because it has to tokenize each line.
+- A plain string `--delimiter` should be preferred over a regular expression
+  delimiter.
 - `--with-nth` makes fzf slower as fzf has to tokenize and reassemble each
   line.