Today I am configuring spell correction in Solr 5.5. Enabling it is not very hard. Simply select which spellcheck component you want to use, please see here for the alternatives: https://cwiki.apache.org/confluence/display/solr/Spell+Checking
There are several but I selected solr.IndexBasedSpellChecker which works for what I need. I replaced the one that comes in the solrconfig and then added spellcheck as lastcomponents. Reindexed, committed and it works.
Most people stop here, but I wanted to learn more, and so here is some very good recommended lecture to understand spellchecking better:
Which references a more technical post
That goes even into more technical depth