Update ChangeLog and documentation

ChangeLog

@@ -9,7 +9,7 @@ Version 1.2.0 (unreleased)
 * Remove automatic software update from the user interface
 * New API methods (not backward compatible)
 * Fever API tokens are longer than before
-* Always update feed URL to avoid useless redirections for futures requests
+* Always update feed URL to avoid useless redirection for futures requests
 * Add support for Wallabag service
 * Show last parsing error message in user interface
 * Disable automatically a feed after too many failures
@@ -20,4 +20,9 @@ Migration procedure from 1.1.x to 1.2.0:
 
 To import your old database to the new database format, use this script:
 
-    php scripts/migrate-db.php --sqlite-db=/path/to/my/db.sqlite --admin==1
+    php scripts/migrate-db.php --sqlite-db=/path/to/my/db.sqlite --admin=1
+
+Previous versions
+-----------------
+
+See commit history or news posted on the website.

docs/upgrade.markdown

@@ -1,7 +1,10 @@
 Upgrade to a new version
 ========================
 
-Before to do anything, **you must backup your data!**
+### Prerequisites
+
+- **You must backup your data!**
+- **You must read the [ChangeLog](https://github.com/miniflux/miniflux/blob/master/ChangeLog) to check for breaking changes**
 
 ### From the archive (stable version)
 
@@ -18,4 +21,7 @@ Before to do anything, **you must backup your data!**
 2. `git pull`
 3. Login and check if everything is OK
 
-Note: Always make a backup of your database before!
+### Notes
+
+- Upgrading from version 1.1.x to 1.2.x require a manual database conversion,
+the procedure is documented in the [ChangeLog](https://github.com/miniflux/miniflux/blob/master/ChangeLog)