Corrected latex workshop vscode extension

.docker/gitpod/Dockerfile

@@ -1,5 +1,6 @@
 # This is the Dockerfile for `algoxy:gitpod`.
 
+# Debian based image from https://gitlab.com/islandoftex/images/texlive
 FROM texlive/texlive:latest
 
 USER root

.gitpod.yml

@@ -3,7 +3,7 @@ image:
 
 vscode:
   extensions:
-    - latex-workshop
+    - James-Yu.latex-workshop
 
 tasks:
   - init: make

README.md

@@ -33,11 +33,11 @@ Contents
 Install
 --------
 
-You may use [gitpod](https://gitpod.io/new#https://github.com/liuxinyu95/algoxy) to build the PDF book from cloud desktop. For local build, you need TeXLive. We use LuaLaTeX, an extended version of TeX.
+You may use [gitpod](https://gitpod.io/#https://github.com/liuxinyu95/algoxy) to build the PDF book from cloud desktop. (It takes about 15 ~ 20 min to build the workspace at the first time, while [later access](https://gitpod.io/workspaces) is quick.) For local build, you need TeXLive. We use LuaLaTeX, an extended version of TeX.
 
 ### Install TeXLive
 
-In Debian/Ubuntu like Linux environment, do **NOT** install the TeXLive through apt-get. Go to TeXLive [official site](https://tug.org/texlive/) to download the setup script. In Windows, TeXLive provides a [gui based installer](https://tug.org/texlive/windows.html), in Mac OS X, there's a [MacTeX](https://www.tug.org/mactex/).
+In Linux/Unix like environment, do **NOT** install the TeXLive through package manager (e.g. apt-get or apk). Go to TeXLive [official site](https://tug.org/texlive/) to download the setup script. In Windows, TeXLive provides a [gui based installer](https://tug.org/texlive/windows.html), in Mac OS X, there's a [MacTeX](https://www.tug.org/mactex/).
 
 ### Others