Add examples of the Text service to README/init (#17)

This adds the Text service as the first example seen. It balances the Chat service, which will always come first alphabetically.

Author: markmcd

README.md

@@ -18,10 +18,18 @@ Get an [API key from MakerSuite](https://makersuite.google.com/app/apikey), then
 ```python
 import google.generativeai as palm
 
-palm.configure(api_key=os.environ['PALM_API_KEY'])
+palm.configure(api_key=os.environ["PALM_API_KEY"])
 ```
 
-Use the `palm.chat` function to have a discussion with a model.
+Use [`palm.generate_text`](https://developers.generativeai.google/api/python/google/generativeai/generate_text)
+to have the model complete some initial text.
+```python
+response = palm.generate_text(prompt="The opposite of hot is")
+print(response.result)  # cold.
+```
+
+Use [`palm.chat`](https://developers.generativeai.google/api/python/google/generativeai/chat)
+to have a discussion with a model.
 ```python
 response = palm.chat(messages=["Hello."])
 print(response.last) #  'Hello! What can I help you with?'

google/generativeai/__init__.py

@@ -21,17 +21,27 @@
 ```
 
 ```
-import google.generativeai as genai
+import google.generativeai as palm
 
-genai.configure(api_key=os.environ['API_KEY'])
+palm.configure(api_key=os.environ['API_KEY'])
+```
+
+## Text
+
+Use the `palm.generate_text` function to have the model complete some initial
+text.
+
+```
+response = palm.generate_text(prompt="The opposite of hot is")
+print(response.result) #  'cold.'
 ```
 
 ## Chat
 
-Use the `genai.chat` function to have a discussion with a model:
+Use the `palm.chat` function to have a discussion with a model:
 
 ```
-response = genai.chat(messages=["Hello."])
+response = palm.chat(messages=["Hello."])
 print(response.last) #  'Hello! What can I help you with?'
 response.reply("Can you tell me a joke?")
 ```
@@ -40,17 +50,17 @@
 
 Use the model service discover models and find out more about them:
 
-Use `genai.get_model` to get details if you know a model's name:
+Use `palm.get_model` to get details if you know a model's name:
 
 ```
-model = genai.get_model('chat-bison-001') # 🦬
+model = palm.get_model('chat-bison-001') # 🦬
 ```
 
-Use `genai.list_models` to discover models:
+Use `palm.list_models` to discover models:
 
 ```
 import pprint
-for model in genai.list_models():
+for model in palm.list_models():
     pprint.pprint(model) # 🦎🦦🦬🦄
 ```