docs: Tweak .gitignore

* Remove ignores for removed docs.
* Introduce blanket ignores for the "output" directories, including txt/ which
  was previously missing.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

.gitignore

@@ -40,48 +40,11 @@ config/Toplevel.mk
 
 build-*
 dist/*
-docs/autom4te.cache/
-docs/config.log
-docs/config.status
-docs/*.aux
-docs/*.dvi
-docs/*.log
-docs/*.pdf
-docs/*.ps
-docs/*.toc
-docs/api/*
-docs/figs/xenserver.eps
-docs/html/*
-docs/interface/WARNINGS
-docs/interface/images.pl
-docs/interface/images.tex
-docs/interface/img1.png
-docs/interface/index.html
-docs/interface/interface.css
-docs/interface/interface.html
-docs/interface/labels.pl
+docs/html/
 docs/man1/
 docs/man5/
-docs/pdf/*
-docs/ps/*
-docs/user/WARNINGS
-docs/user/images.pl
-docs/user/images.tex
-docs/user/img1.png
-docs/user/img2.png
-docs/user/img3.png
-docs/user/index.html
-docs/user/internals.pl
-docs/user/labels.pl
-docs/user/user.css
-docs/user/user.html
-docs/xen-api/vm_lifecycle.eps
-docs/xen-api/xenapi-datamodel-graph.eps
-docs/xen-api/xenapi.out
-docs/xen-api/xenapi.dvi
-docs/xen-api/xenapi.pdf
-docs/xen-api/xenapi.ps
-docs/xen-api/xenapi.toc
+docs/pdf/
+docs/txt/
 extras/mini-os/include/mini-os
 extras/mini-os/include/x86/mini-os
 extras/mini-os/include/xen