README: clarifications for calling multiple checkers.

README.markdown

@@ -201,6 +201,30 @@ let g:syntastic_php_checkers = ['php', 'phpcs', 'phpmd']
 This is telling syntastic to run the `php` checker first, and if no errors are
 found, run `phpcs`, and then `phpmd`.
 
+You can also run checkers explicitly by calling `:SyntasticCheck <checker>`.
+
+e.g. to run `phpcs` and `phpmd`:
+```vim
+:SyntasticCheck phpcs phpmd
+```
+
+This works for any checkers available for the current filetype, even if they
+aren't listed in `g:syntastic_<filetype>_checkers`.  You can't run checkers for
+"foreign" filetypes though (e.g. you can't run, say, a Python checker if the
+current filetype is `php`).
+
+<a name="faqaggregate"></a>
+
+__Q. How can I display together the errors found by all checkers enabled for
+the current file?__
+
+A. Set `g:syntastic_aggregate_errors` to 1 in your vimrc:
+```vim
+let g:syntastic_aggregate_errors = 1
+```
+
+See `:help syntastic-aggregating-errors` for more details.
+
 <a name="faqlnext"></a>
 
 __Q. How can I jump between the different errors without using the location

plugin/syntastic.vim

@@ -18,7 +18,7 @@ if has('reltime')
     let g:syntastic_start = reltime()
 endif
 
-let g:syntastic_version = '3.4.0-26'
+let g:syntastic_version = '3.4.0-27'
 
 " Sanity checks {{{1