MAINT: gitignore vim (#40)

* I still see swap files for vim with this project, so use
more standard ignores from:
https://github.com/github/gitignore/blob/main/Global/Vim.gitignore

[skip ci]

Author: tylerjereddy

.gitignore

@@ -4,7 +4,12 @@
 /.vscode
 /*.nja
 settings.json
-*.swp
+# vim swap files
+[._]*.s[a-v][a-z]
+[._]*.sw[a-p]
+[._]s[a-rt-v][a-z]
+[._]ss[a-gi-z]
+[._]sw[a-p]
 
 # Edit files
 *~