docs: clean main vignette

Author: dshemetov

vignettes/epidatr.Rmd

@@ -1,7 +1,5 @@
 ---
 title: "Delphi Epidata R API Client"
-author: "Delphi Group"
-date: "`r Sys.Date()`"
 output: rmarkdown::html_vignette
 vignette: >
   %\VignetteIndexEntry{Delphi Epidata R API Client}
@@ -16,8 +14,6 @@ library(epidatr)
 library(dplyr)
 ```
 
-# Delphi Epidata R API Client
-
 ## Basic Usage
 
 Fetching some data from the Delphi Epidata API is simple.