Documenting the addition of patterns with Liquibase

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Since new patterns are no longer added with an SQL dump, as documented in the readme, the new method using Liquibase must be documented.

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Liquibase command:
./liquibase generate-changelog --url=jdbc:postgresql://127.0.0.1:5060/patternatlas --username=patternatlas --password=patternatlas --diff-types="data" --changelog-file="././out.xml"