fix comment typo

Closes #424

github/search.go

@@ -70,7 +70,7 @@ func (s *SearchService) Issues(query string, opt *SearchOptions) (*IssuesSearchR
 	return result, resp, err
 }
 
-// UsersSearchResult represents the result of an issues search.
+// UsersSearchResult represents the result of a users search.
 type UsersSearchResult struct {
 	Total             *int   `json:"total_count,omitempty"`
 	IncompleteResults *bool  `json:"incomplete_results,omitempty"`
@@ -105,7 +105,7 @@ func (tm TextMatch) String() string {
 	return Stringify(tm)
 }
 
-// CodeSearchResult represents the result of an code search.
+// CodeSearchResult represents the result of a code search.
 type CodeSearchResult struct {
 	Total             *int         `json:"total_count,omitempty"`
 	IncompleteResults *bool        `json:"incomplete_results,omitempty"`