Would like to contribute to wiki

[sm8ps]

I would add something like the following to the page Errors. However, the wiki is not writeable. Would somebody want to copy this and edit to their suits?

### After upgrade

In the log file (typically '/var/log/elasticsearch/elasticsearch.log'):
java.lang.IllegalArgumentException: Plugin [ingest-attachment] was built for Elasticsearch version A.B.C but version D.E.F is running

_You need to upgrade the ingest-attachment plugin._
First, uninstall your current version:
/usr/share/elasticsearch/bin/elasticsearch-plugin remove ingest-attachment
Then install the new version:
/usr/share/elasticsearch/bin/elasticsearch-plugin install ingest-attachment

[C0rn3j]

The wiki also needs to switch from mentioning ES 6 to ES7 and add mention of occ fulltextsearch:test