Add a requirements file

Doing this because I have to keep looking it up every time I want to know.  It really should be in our repo in addition to our wiki/site.

other/requirements.md

@@ -0,0 +1,57 @@
+# SMF Miniumn Requirements
+
+## PHP
+### PHP Version Support
+| MIN SMF VERSION | MAX SMF VERSION | MIN PHP VERSION | MAX PHP VERSION |
+| ------ | ------ | ------ | ------ |
+| 2.1    | LATEST | 7.0.0  | 8.1.0  |
+
+### Undocumented Version Support
+- Versions below miniumn listed above are not supported
+- Versions above the maxiumn listed above:
+	- Will be supported in a future date unless this version has reached End of Life
+	- Support is limited until then and provided as best effort
+	- Git Repo may contain code testing support
+
+### PHP INI
+- engine directive must be set to On
+- session.save_path directive must be set to a valid directory or empty
+- file_uploads directive must be set to On
+- upload_tmp_dir directive must be set to a valid directory or empty
+
+### Additional PHP Libraires
+- mbstring extension
+- fileinfo extension
+
+## Database Engine
+### [MySQL](http://www.mysql.com)
+- MySQL 5.6
+
+### [PostgreSQL](http://www.postgresql.org)
+- PostgreSQL 9.6
+- standard_conforming_strings must be set to on
+
+## Web Server
+### Apache
+- Apache Web Server 2.2 or 2.4 with mod_php
+
+### FastCGI/FPM
+- Any Web server capable of FastCGI supporting PHP FPM
+
+
+# Recommenations
+
+## PHP Recommenations
+### Recommended PHP INI
+- max_input_time set to a value of at least 30.
+- post_max_size and upload_max_filesize set to the size of the largest attachments you wish to be able to - upload.
+- memory_limit set to at least 512M.
+- max_execution_time set to at least 15.
+- session.use_trans_sid set to Off.
+
+### Recommended PHP Libraires
+- GD Graphics Library 2.0 or higher.
+
+## Web Server
+### Apache
+- mod_security disabled (please see Mod security for more information).