Vim doesn't show plugin documentation

Question

When I put a symbolic link to a .txt documentation plugin, vim doesn't show me the help

Example: I have in ~/.vim/doc

 $ ls -al NERD_tree.txt 
 NERD_tree.txt -> PATH/nerdtree/doc/NERD_tree.txt

in vim:

:h NERDtree

This command doesn't show the documentation.

Answer 1

Vim needs to know when the help files are updated, so it can know where the NERDtree tag should point. Running the following in vim should fix it:

:helptags ~/.vim/doc