update doc for 1.5.1

Author: skywind3000

README.cn.md

@@ -341,6 +341,26 @@ alias zh='z -I -t .'
 
 第一列数据代表该路径多少秒以前访问过，第二列是路径名称。此时，你可以试着敲几个字母，用 fzf 的字符串模糊匹配进行定位，或者用光标键的上和下（CTRL+J/K 也可以）来上下移动，最后按回车 cd 过去，或者 ESC 放弃。
 
+版本 `v1.5.1` 引入了模拟 "dir stack" 可以通过： `z -`，`z --` 和 `z -{num}` 来操作:
+
+```bash
+# 显示当前的 dir stack
+$ z --    
+ 0  /home/skywind/work/match/memory-match
+ 1  /home/skywind/.local/etc
+ 2  /home/skywind/software/vifm-0.9.1
+ 3  /home/skywind/work
+ 4  /home/skywind/work/match
+
+# cd 到栈里 2 号路径
+$ z -2
+  => cd /home/skywind/software/vifm-0.9.1
+
+# 弹出栈顶 (cd 到上一次的老路径)，和 "z -0" 相同
+$ z -
+  => cd -
+```
+
 注意：最好把增强匹配模式打开，这样查看历史路径时可以把当前路径过滤掉。
 
 ## Tips

README.md

@@ -355,11 +355,32 @@ The new alias `zh` (jump to history) uses a parameter `-t` to sort the result by
 
 The first column indicates how many seconds ago you have visited, and the second column is the path name. With `zh`, you can type some character to use string matching in fzf, or use `<Up>`/`<Down>` (as well as `CTRL+j/k`) to move the selector (red `>`) up and down. 
 
-At last, press `<enter>` to accept or `<ESC>` to give up.
+At last, press `<enter>` to accept or `<ESC>` to give up. 
+
+Version `v1.5.1` has introduced a simulated "dir stack", which can be manipulated by `z -`, `z --` and `z -{num}`:
+
+```bash
+# display current dir stack
+$ z --    
+ 0  /home/skywind/work/match/memory-match
+ 1  /home/skywind/.local/etc
+ 2  /home/skywind/software/vifm-0.9.1
+ 3  /home/skywind/work
+ 4  /home/skywind/work/match
+
+# cd to the 2nd directory in the stack
+$ z -2
+  => cd /home/skywind/software/vifm-0.9.1
+
+# popup stacktop (cd to previous directory), same as "z -0"
+$ z -
+  => cd -
+```
 
 Remember to enable the [enhanced matching](#enhanced-matching) algorithm, the current working directory can be skipped with it.
 
 
+
 ## Tips
 
 Recommended aliases you may find useful:
@@ -427,6 +448,7 @@ As you see, z.lua is the fastest one and requires less resource.
 
 ## History
 
+- 1.5.1 (2019-02-15): new: simulated dir stack by `z -`, `z --` and `z -{num}`.
 - 1.5.0 (2019-02-14): fixed minor issues in backward jumping.
 - 1.4.7 (2019-02-13): Don't use regex in backward jumping (use plain text instead).
 - 1.4.6 (2019-02-12): change: `_ZL_EXCLUDE_DIRS` to a comma separated list of dirs to exclude.