shared_ptr: add some documentation
shared_ptr: add some documentation

xtao/seastar,shyamalschandra/seastar,jonathanleang/seastar,wildinto/seastar,dreamsxin/seastar,leejir/seastar,rluta/scylla,scylladb/scylla-seastar,senseb/scylla,mixja/seastar,flashbuckets/seastar,bowlofstew/scylla,chunshengster/seastar,jonathanleang/seastar,avikivity/seastar,flashbuckets/seastar,scylladb/scylla,cloudius-systems/seastar,raphaelsc/seastar,glommer/scylla,raphaelsc/seastar,bowlofstew/scylla,guiquanz/scylla,printedheart/seastar,syuu1228/seastar,bowlofstew/seastar,linearregression/seastar,hongliangzhao/seastar,wildinto/seastar,kangkot/scylla,dwdm/seastar,bzero/seastar,justintung/scylla,rentongzhang/scylla,bowlofstew/scylla,leejir/seastar,syuu1228/seastar,linearregression/scylla,capturePointer/scylla,xtao/seastar,syuu1228/seastar,dwdm/scylla,asias/scylla,slivne/seastar,ducthangho/imdb,stamhe/scylla,dwdm/seastar,kangkot/scylla,tempbottle/scylla,norcimo5/seastar,duarten/scylla,senseb/scylla,glommer/scylla,dwdm/scylla,raphaelsc/scylla,avikivity/seastar,mixja/seastar,avikivity/scylla,scylladb/scylla-seastar,scylladb/seastar,slivne/seastar,linearregression/seastar,norcimo5/seastar,bzero/seastar,victorbriz/scylla,victorbriz/scylla,bzero/seastar,kjniemi/seastar,victorbriz/scylla,scylladb/seastar,cloudius-systems/seastar,acbellini/scylla,acbellini/seastar,dwdm/seastar,phonkee/scylla,joerg84/seastar,tempbottle/seastar,asias/scylla,shaunstanislaus/scylla,joerg84/seastar,acbellini/scylla,capturePointer/scylla,scylladb/scylla-seastar,acbellini/seastar,leejir/seastar,avikivity/seastar,ducthangho/imdb,capturePointer/scylla,gwicke/scylla,raphaelsc/seastar,hongliangzhao/seastar,mixja/seastar,tempbottle/seastar,gwicke/scylla,sjperkins/seastar,shaunstanislaus/scylla,kjniemi/seastar,acbellini/seastar,aruanruan/scylla,avikivity/scylla,respu/scylla,guiquanz/scylla,scylladb/seastar,slivne/seastar,tempbottle/scylla,rentongzhang/scylla,duarten/scylla,stamhe/seastar,linearregression/scylla,linearregression/scylla,phonkee/scylla,koolhazz/seastar,hongliangzhao/seastar,printedheart/seastar,jonathanleang/seastar,eklitzke/scylla,asias/scylla,aruanruan/scylla,anzihenry/seastar,gwicke/scylla,rluta/scylla,bowlofstew/seastar,shaunstanislaus/scylla,flashbuckets/seastar,kjniemi/scylla,justintung/scylla,anzihenry/seastar,wildinto/scylla,kjniemi/seastar,kangkot/scylla,chunshengster/seastar,stamhe/seastar,joerg84/seastar,cloudius-systems/seastar,koolhazz/seastar,printedheart/seastar,acbellini/scylla,glommer/scylla,scylladb/scylla,raphaelsc/scylla,tempbottle/scylla,phonkee/scylla,ducthangho/imdb,respu/scylla,rentongzhang/scylla,koolhazz/seastar,anzihenry/seastar,linearregression/seastar,respu/scylla,sjperkins/seastar,raphaelsc/scylla,avikivity/scylla,duarten/scylla,justintung/scylla,scylladb/scylla,wildinto/scylla,stamhe/scylla,scylladb/scylla,sjperkins/seastar,eklitzke/scylla,tempbottle/seastar,senseb/scylla,dwdm/scylla,rluta/scylla,shyamalschandra/seastar,guiquanz/scylla,wildinto/seastar,dreamsxin/seastar,bowlofstew/seastar,chunshengster/seastar,norcimo5/seastar,kjniemi/scylla,eklitzke/scylla,shyamalschandra/seastar,wildinto/scylla,aruanruan/scylla,kjniemi/scylla,xtao/seastar,stamhe/scylla,dreamsxin/seastar,stamhe/seastar