Add kernel doc to extra_dist.
Add kernel doc to extra_dist.

davidgaleano/libwebsockets,davidgaleano/libwebsockets,tvanderbruggen/libwebsockets,tvanderbruggen/libwebsockets,tvanderbruggen/libwebsockets,tvanderbruggen/libwebsockets,davidgaleano/libwebsockets,tvanderbruggen/libwebsockets,davidgaleano/libwebsockets