Add changelog

Author: zachborboa

CHANGELOG.md

@@ -0,0 +1,31 @@
+# Change Log
+
+PHP Curl Class uses semantic versioning with version numbers written as `MAJOR.MINOR.PATCH`. You may safely update
+`MINOR` and `PATCH` version changes. It is recommended to review `MAJOR` changes prior to upgrade as there may be
+backwards-incompatible changes that will affect existing usage.
+
+### Changes
+
+(TODO: Add changes for next `MAJOR` version release.)
+
+### Manual Review
+
+Manually view changes on the [comparison page](https://github.com/php-curl-class/php-curl-class/compare/). For example,
+visit [7.4.0...8.0.0](https://github.com/php-curl-class/php-curl-class/compare/7.4.0...8.0.0) to compare the changes for
+the `MAJOR` upgrade from 7.4.0 to 8.0.0. Comparing against `HEAD` is also possible using the `tag...HEAD` syntax
+([8.3.0...HEAD](https://github.com/php-curl-class/php-curl-class/compare/8.3.0...HEAD)).
+
+View the log between releases:
+
+    $ git fetch --tags
+    $ git log 7.4.0...8.0.0
+
+View the code changes between releases:
+
+    $ git fetch --tags
+    $ git diff 7.4.0...8.0.0
+
+View only the source log and code changes between releases:
+
+    $ git log 7.4.0...8.0.0 "src/"
+    $ git diff 7.4.0...8.0.0 "src/"