Change details in ERRATUM.md, UPGRADE.md

ERRATUM.md

@@ -2,6 +2,27 @@
 
 The following are the erratum for each `README.md` found from the previous versions:
 
+## 0.9.0
+
+This version introduced a PSR-15 implementation based on `http-interop/http-middleware`. With this, kindly add the said package and update the packages using `composer update`:
+
+``` diff
+ {
+     "require":
+     {
+         "filp/whoops": "~1.0",
++        "http-interop/http-middleware": "0.4.1",
+         "nikic/fast-route": "~1.0",
+         "rdlowrey/auryn": "~1.0",
+-        "rougin/slytherin": "~0.8.0",
++        "rougin/slytherin": "~0.9.0",
+         "twig/twig": "~1.0",
+         "zendframework/zend-diactoros": "~1.0",
+         "zendframework/zend-stratigility": "~1.0"
+     }
+ }
+```
+
 ## 0.4.0
 
 In this version, the `patricklouys/http` has been removed in favor for PSR-07 (`psr/http-message`). With this, kindly add a package that is compliant to PSR-07 (e.g., `zendframework/zend-diactoros`) in the `composer.json`:
@@ -29,7 +50,7 @@ Perform `composer update` afterwards to update the specified packages.
 
 ### Usage
 
-As per documentation, implementing interfaces are required to use Slytherin components. However in this release, the implemented third-party packages are not included (e.g., `patricklouys/http`, etc.) and needs to be installed manually. Kindly include the said packages in the `composer.json`:
+As per documentation, implementing interfaces are required to use Slytherin components. However in this version, the implemented third-party packages are not included (e.g., `patricklouys/http`, etc.) and needs to be installed manually. Kindly include the said packages in the `composer.json`:
 
 ``` diff
  {

UPGRADE.md

@@ -2,6 +2,30 @@
 
 Below are the guides when upgrading from specified versions due to backward compatibility breaks:
 
+## From `v0.6.0` to `v0.7.0`
+
+Although no backward compatibility issues found in Slytherin's code, one of the Slytherin's supported packages, `filp/whoops`, has an issue regarding PHP errors. With this, kindly change its version to `~2.0` in the `composer.json` then perform `composer update` after:
+
+``` diff
+ {
+     "require":
+     {
+-        "filp/whoops": "~1.0",
++        "filp/whoops": "~2.0",
+     }
+ }
+```
+
+See the [Issue #341](https://github.com/filp/whoops/issues/341) from the `filp/whoops` repository for reference.
+
+## From `v0.5.0` to `v0.6.0`
+
+No known backward compatibility issues found.
+
+## From `v0.4.0` to `v0.5.0`
+
+No known backward compatibility issues found.
+
 ## From `v0.3.0` to `v0.4.0`
 
 The `v0.4.0` version requires a PSR-07 compliant package. See the `v0.4.0` in `ERRATUM` for updating the `composer.json`.