polish installation

Author: Roger-luo

README.md

@@ -13,10 +13,19 @@ The CI infrastructure for automated performance testing of the Julia language is
 
 ## Installation
 
-To install BenchmarkTools, you can run the following:
+<p>
+BenchmarkTools is a &nbsp;
+    <a href="https://julialang.org">
+        <img src="https://raw.githubusercontent.com/JuliaLang/julia-logo-graphics/master/images/julia.ico" width="16em">
+        Julia Language
+    </a>
+    &nbsp; package. To install BenchmarkTools,
+    please <a href="https://docs.julialang.org/en/v1/manual/getting-started/">open
+    Julia's interactive session (known as REPL)</a> and press <kbd>]</kbd> key in the REPL to use the package mode, then type the following command
+</p>
 
 ```julia
-Pkg.add("BenchmarkTools")
+pkg> add BenchmarkTools
 ```
 
 ## Documentation