Update 00.index.md (#82)

Update description wording

Tested out the "Edit this page" link from the staging website, works
pretty easily and allows for creating a "patch" branch to create the PR.

content/00.build/00.index.md

@@ -1,6 +1,6 @@
 ---
 title: Introduction
-description: Welcome to zkSync Era Docs.
+description: Welcome to the zkSync Era Docs.
 ---
 
 **zkSync Era** is a Layer 2