Updated faq (markdown)

faq.md

@@ -140,6 +140,18 @@ If you're on Windows using cygwin and the above ruby command fails with:
 resolve the problem. In the meantime, you can set `g:plug_threads` to 1, so that
 Ruby installer is not used at all.
 
+### YouCompleteMe timeout
+
+[YouCompleteMe (YCM)](https://github.com/Valloric/YouCompleteMe) is a huge project and you might run into timeouts when trying to install/update it with vim-plug.
+
+The parallel installer of vim-plug (ruby or python) times out only when the stdout of the process is not updated for the designated seconds (default 60). Which means even if the whole process takes much longer than 60 seconds to complete, if the process is constantly printing the progress to stdout (`10%`, `11%`, ...) it should never time out. Nevertheless, we still experience problems when installing YCM :(
+
+Workarounds are as follows:
+- Increase `g:plug_timeout`
+- Install YCM exclusively with `:PlugInstall YouCompleteMe`
+    - In this case single-threaded vimscript installer, which never times out, is used
+- Asynchronous Neovim installer does not implement timeout.
+
 ### Errors on fish shell
 
 If vim-plug doesn't work correctly on fish shell, you might need to add `set