func (s ReactionsService) CreateCommentReaction(owner, repo string, id int, content string) (*Reaction, *Response, error) {
	u := fmt.Sprintf("repos/%v/%v/comments/%v/reactions", owner, repo, id)
	body := &Reaction{Content: String(content)}
	req, err := s.client.NewRequest("POST", u, body)
	if err != nil {
		return nil, nil, err
	}
	req.Header.Set("Accept", mediaTypeReactionsPreview)
	m := &Reaction{}
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, nil
}
CreateCommentReaction creates a reaction for a commit comment.
Note that if you have already created a reaction of type content, the
previously created reaction will be returned with Status: 200 OK.

GitHub API docs: https://developer.github.com/v3/reactions/#create-reaction-for-a-commit-comment
package github
import "fmt"
type ReactionsService service
type Reaction struct {
	ID   *int  `json:"id,omitempty"`
	User *User `json:"user,omitempty"`
	Content *string `json:"content,omitempty"`
}
type Reactions struct {
	TotalCount *int    `json:"total_count,omitempty"`
	PlusOne    *int    `json:"+1,omitempty"`
	MinusOne   *int    `json:"-1,omitempty"`
	Laugh      *int    `json:"laugh,omitempty"`
	Confused   *int    `json:"confused,omitempty"`
	Heart      *int    `json:"heart,omitempty"`
	Hooray     *int    `json:"hooray,omitempty"`
	URL        *string `json:"url,omitempty"`
}
func (r Reaction) String() string {
	return Stringify(r)
}
func (s *ReactionsService) ListCommentReactions(owner, repo string, id int, opt *ListOptions) ([]*Reaction, *Response, error) {
	u := fmt.Sprintf("repos/%v/%v/comments/%v/reactions", owner, repo, id)
	u, err := addOptions(u, opt)
	if err != nil {
		return nil, nil, err
	}
	req, err := s.client.NewRequest("GET", u, nil)
	if err != nil {
		return nil, nil, err
	}
	req.Header.Set("Accept", mediaTypeReactionsPreview)
	var m []*Reaction
	resp, err := s.client.Do(req, &m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, nil
}