Mention ram limits

We do have that setting in the installation instructions, but we never explain what it's for, so people don't see it / don't copy it.

content/en/docs/install/faqs.md

@@ -17,7 +17,7 @@ There are 2 problems here:
   appreciated)
 
 To tell `nodejs` to allocate up to (for example) 8GiB (8192MiB), you
-can set the environmnt variable `NODE_OPTIONS`:
+can set the environment variable `NODE_OPTIONS`:
 
 ```bash
 export NODE_OPTIONS='--max-old-space-size=8192'