Cleanup gitignore a bit

Remove unneeded gitignore files
Cleanup normal gitignore file a bit:
* Add Build results comment
* add slash to .tox to mark it as directory

Change-Id: I9a82a6353e3b8cec186e8b688489916d9355f0da

.gitignore

@@ -1,16 +1,18 @@
 .DS_Store
-target/
 *.xpr
 .idea
+
+# Build results
+target/
 bk-ha-guide.xml
 
-#Ignore Vagrant Related Files
+# Ignore Vagrant Related Files
 acceptance_config.yml
 boxes/*
 /.vagrant
 
 # Testenvironment
-.tox
+.tox/
 
 # Editors
 *~

doc/user-guide-admin/.gitignore

@@ -1,4 +0,0 @@
-.DS_Store
-target/
-*.bak
-src/.DS_Store

doc/user-guide/.gitignore

@@ -1,4 +0,0 @@
-.DS_Store
-target/
-*.bak
-src/.DS_Store