Add install prereq. (#800)

Ref: #793 (comment) by @rootulp
celestiaorg · Sep 27, 2022 · 60f341a · 60f341a
1 parent dac49d1
commit 60f341a
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/specs/README.md b/specs/README.md
@@ -2,6 +2,8 @@
 
 ## Building From Source
 
+Prerequisite: [install mdBook](https://rust-lang.github.io/mdBook/guide/installation.html).
+
 To build book:
 
 ```sh