Put s:wig2cmd() and s:setcwd() into docs

Close #70

doc/ctrlp.txt

@@ -720,6 +720,48 @@ Statuslines:~
 
   For rebuilding the statuslines, see |g:ctrlp_status_func|.
 
+===============================================================================
+CUSTOM-CONFIGS                                           *ctrlp-custom-configs*
+
+* Use |wildignore| for |g:ctrlp_user_command|:
+>
+  function! s:wig2cmd()
+    " Change wildignore into space or | separated groups
+    " e.g. .aux .out .toc .jpg .bmp .gif
+    " or   .aux$\|.out$\|.toc$\|.jpg$\|.bmp$\|.gif$
+    let pats = ['[*\/]*\([?_.0-9A-Za-z]\+\)\([*\/]*\)\(\\\@<!,\|$\)','\\\@<!,']
+    let subs = has('win32') || has('win64') ? ['\1\3', ' '] : ['\1\2\3', '\\|']
+    let expr = substitute(&wig, pats[0], subs[0], 'g')
+    let expr = substitute(expr, pats[1], subs[1], 'g')
+    let expr = substitute(expr, '\\,', ',', 'g')
+
+    " Set the user_command option
+    let g:ctrlp_user_command = has('win32') || has('win64')
+      \ ? 'dir %s /-n /b /s /a-d | findstr /V /l "'.expr.'"'
+      \ : 'find %s -type f | grep -v "'.expr .'"'
+  endfunction
+
+  call s:wig2cmd()
+<
+(submitted by Rich Alesi <github.com/ralesi>)
+
+* Set the working directory to the project’s root, or to the parent directory
+  of the current file if a root can’t be found:
+>
+  function! s:setcwd()
+    let cph = expand('%:p:h', 1)
+    if match(cph, '\v^<.+>://') >= 0 | retu | en
+    for mkr in ['.git/', '.hg/', '.svn/', '.bzr/', '_darcs/', '.vimprojects']
+      let wd = call('find'.(mkr =~ '/$' ? 'dir' : 'file'), [mkr, cph.';'])
+      if wd != '' | let &acd = 0 | brea | en
+    endfo
+    exe 'lc!' fnameescape(wd == '' ? cph : substitute(wd, mkr.'$', '.', ''))
+  endfunction
+
+  autocmd BufEnter * call s:setcwd()
+<
+(requires Vim 7.1.299+)
+
 ===============================================================================
 CREDITS                                                         *ctrlp-credits*