docs: pin examples to opendecree>=0.3.0a1 and document --pre install

examples/requirements.txt pinned to >=0.3.0a1 so pip resolves the
current alpha release. README prerequisites section updated with
--pre flag and alpha-status note.

Closes #66

Co-Authored-By: Claude <noreply@anthropic.com>

Author: zeevdr

examples/README.md

@@ -18,8 +18,10 @@ The tenant ID is written to `.tenant-id` — examples read it automatically.
 
 ## Prerequisites
 
+OpenDecree is currently in alpha. Install with the `--pre` flag so pip's resolver includes pre-release versions:
+
 ```bash
-pip install opendecree
+pip install --pre opendecree
 ```
 
 For the FastAPI example, also install:

examples/requirements.txt

@@ -1 +1 @@
-opendecree>=0.1.0
+opendecree>=0.3.0a1