.gitignore: remove editor related section

Individuals (namely me) should just set a personal excludesfile.

Change-Id: I0417495de7a87346e61224da84c50ce70b2c3900
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/238439
Reviewed-by: Jonathan Amsterdam <jba@google.com>

.gitignore

@@ -32,9 +32,5 @@ go-discovery*.json
 *credentials.yaml
 *.gcloudignore
 
-#### Editor Related Files ####
-tags
-env*.sh
-
 #### Loadtest Related Files ####
 results.bin