[README] add Requirements section (#1000)

* [README] add Requirements section

This is based user feedback and testing. This may expand if need be
Signed-off-by: NAyane Satomi <chinodesuuu@gmail.com>

* [README] raised the bar a bit more

Apparently we were targeting GLIBC 2.17
Signed-off-by: NAyane Satomi <chinodesuuu@gmail.com>

README.md

@@ -18,6 +18,15 @@ docker run -it -p 127.0.0.1:8080:8080 -v "${HOME}/.local/share/code-server:/home
 ![Screenshot](/doc/assets/ide.gif)
 
 ## Getting Started
+
+### Requirements
+
+- Minimum GLIBC version of 2.17 and a minimum version of GLIBCXX of 3.4.15.
+  - This is the main requirement for building Visual Studio Code. We cannot go lower than this.
+- A 64-bit host with at least 1GB RAM and 2 cores.
+   - 1 core hosts would work but not optimally.
+- Docker (for Docker versions of `code-server`).
+
 ### Run over SSH
 Use [sshcode](https://github.com/codercom/sshcode) for a simple setup.