docs: add connect-pg-simple to list of session stores
docs: add connect-pg-simple to list of session stores

closes #199

happysj/session,soulman-is-good/session,danielgindi/session,gabeio/session,saighost/session,globesherpa/session,cnwhy/session,MadisonReed/session,victorenator/session,hl198181/session,expressjs/session,digitalartcrew/session,socialrank/express-session,wesleytodd/session,fracmak/session