Added the dump.rdb file to gitignore

Whenever i'm working on GitLab I have redis running, but redis is
generating a db dump file called dump.rdb, I dont think that should be
checked in, so it should be on the gitignore list
Update installation.md

just fix typo

fix broken links
No need to edit database.yml for standard Postgres

Postgres running on localhost should recognize the `git` system user
used by GitLab so there is no need to set/change database passwords.
Be more specific about when to edit database.yml
Add patch release document.
EE changelog note.
Link to the doc.
Speed up loading and add pagination to wiki pages page.
Satellite will exist when doing automerge_check.
Make the db and statemachine default is the same
List the next steps.
Update security document with the link to patch document.
Merge branch 'add_patch_release_doc' into 'master'

Add patch release documentation for developers
Merge pull request #6706 from jvanbaarsen/add-dump-rdb-to-ignore

Added the dump.rdb file to gitignore
Merge pull request #6711 from marciotoze/patch-1

Update installation.md
Merge branch 'postgres_installation' into 'master'

No need to edit database.yml for standard Postgres
100k organizations use GitLab.
Merge branch '100k' into 'master'

100k
Merge branch 'link-to-oauth-doc' into 'master'

Link to oauth doc

Possible after https://github.com/gitlabhq/gitlabhq/pull/6741/files
Merge branch 'simple-pointers-in-readme' into 'master'

Simple pointers in readme