code: function mergeForVersions(versions, opts) {
      opts = _.defaults(opts || {}, {
          includeTag: true
      });
  
      return _.chain(versions)
          .reduce(function(prev, version) {
              if (!version.notes) return prev;
  
              // Include tag as title
              if (opts.includeTag) {
                  prev = prev + '## ' + version.tag + '\n';
              }
  
              // Include notes
              prev = prev + version.notes + '\n';
  
              // New lines
              if (opts.includeTag) {
                  prev = prev + '\n';
              }
  
              return prev;
          }, '')
          .value();
  }
docs: Merge release notes for a list of versions