add fail2ban snippet to FAQ

from unguamorray in issue #274

README.md

@@ -533,3 +533,13 @@ ensuring they don't become too large.  The message index database file for an
 account is at `data/accounts/<account>/index.db`, accessed with the bstore
 database library, which uses bbolt (formerly BoltDB) for storage, a
 transactional key/value library/file format inspired by LMDB.
+
+## How do I block IPs with authentication failures with fail2ban?
+
+Mox includes a rate limiter for IPs/networks that cause too many authentication
+failures. It automatically unblocks such IPs/networks after a while. So you may
+not need fail2ban. If you want to use fail2ban, you could use this snippet:
+
+	[Definition]
+	failregex = .*failed authentication attempt.*remote=<HOST>
+	ignoreregex =

develop.txt

@@ -101,10 +101,10 @@ Large files (images/videos) are in https://github.com/mjl-/mox-website-files to
 keep the repository reasonably sized.
 
 The public website may serve the content from the "website" branch. After a
-release release, the main branch (with latest development code and
-corresponding changes to the website about new features) is merged into the
-website branch.  Commits to the website branch (e.g. for a news item, or any
-other change unrelated to a new release) is merged back into the main branch.
+release, the main branch (with latest development code and corresponding
+changes to the website about new features) is merged into the website branch.
+Commits to the website branch (e.g. for a news item, or any other change
+unrelated to a new release) is merged back into the main branch.
 
 
 # TLS certificates