Make deprecation clearer

ChangeLog.txt

@@ -5,9 +5,31 @@ Date: ?-Apr-2021
 Breaking changes:
 - Passing file paths to parse() or new Csv() is now deprecated
   and will be removed in v2.0.0. Use ->parseFile() instead.
-  It will only call trigger_error() for now.
-  This change is to avoid security issues and to make this
-  library easier to learn (less magic).
+
+  WARNING: It will call trigger_error() for now.
+  This may still break your application, depending on your
+  php.ini config. You can add E_USER_DEPRECATED to the
+  error_reporting mask to avoid breaking your application:
+
+  Example:
+
+  error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT & ~E_USER_DEPRECATED
+
+  This change is to avoid security issues: see issue #198.
+
+Non-breaking deprecations:
+- The function load_data() is deprecated.
+  Call loadFile() or loadDataString() instead.
+- Supplying CSV data (file content) to auto() is deprecated.
+  Please use autoDetectionForDataString().
+
+  The motivation is to make subtle gotchas less likely: when the
+  file cannot be found or read by PHP (permissions), its file path
+  would be treated like CSV data.
+- Currently, there is code to parse .php: <?...?> tags are removed
+  before the remaining file content is treated like a .csv file.
+  This rarely-used functionality will be removed in v2.0.0.
+  You are only affected if you use ParseCsv to parse .php files.
 
 New features: none
 Bug fixes: none