Make fetchdf notebook magic a cell magic (#989)

* Change fetchdf magic to cell_magic

* Update notebook reference

* Add %context magic to notebook reference

* Wordsmith

Author: treysp

docs/reference/notebook.md

@@ -1,21 +1,50 @@
 # Notebook
 
-SQLMesh supports Jupyter and Databricks Notebooks. Magics are loaded automatically and use the variable `context` to locate a SQLMesh project.
+SQLMesh supports Jupyter and Databricks Notebooks. Magics are loaded automatically when `sqlmesh` or one of its modules is imported.
+
+## SQLMesh project setup
+
+Notebooks locate a SQLMesh project by setting a `context` with either the Python API or a notebook magic.
+
+Set the context with the Python `Context` function as follows:
 
 ```python
 from sqlmesh import Context
 
 context = Context(paths="path_to_sqlmesh_project")
 ```
 
-To create a fresh project in Databricks using the example project under Get Started, use the following.
+Alternatively, set the context with a notebook magic:
+
+``` python
+import sqlmesh
+
+%context path_to_sqlmesh_project
+```
+
+### Quick start project
+
+If desired, you can create the [quick start example project](../quick_start.md) with the `init_example_project` function:
 
 ```python
 from sqlmesh.cli.example_project import init_example_project
 
-init_example_project("local_dbfs_path")
+init_example_project("path_to_project_directory")
+```
+
+### Databricks notebooks
+To use your Databricks cluster, update the `default_connection` and `test_connection` in the `config.yaml` file. 
+
+See the [Execution Engines](../integrations/engines.md#databricks) page for information on configuring a Databricks connection.
+
+## context
+```
+%context paths
+
+positional arguments:
+  paths                 Path(s) to one ore more directories containing SQLMesh 
+                        projects
 ```
-Update the `default_connection` and `test_connection` in the config.yaml file to use your Databricks cluster. For Databricks connection configuration, see the [Execution Engines](https://sqlmesh.readthedocs.io/en/stable/integrations/engines/) page.
 
 ## plan
 ```
@@ -105,12 +134,13 @@ options:
 
 ## fetchdf
 ```
-%fetchdf [df_var]
+%%fetchdf [df_var]
 
-Fetches a dataframe from sql, optionally storing it in a variable.
+Fetch a dataframe with a cell's SQL query, optionally storing it in a variable.
 
 positional arguments:
-  df_var  An optional variable name to store the resulting dataframe.
+  df_var                An optional variable name to store the resulting 
+                        dataframe.
 ```
 
 ## test

sqlmesh/magics.py

@@ -4,7 +4,13 @@
 from collections import defaultdict
 
 from IPython.core.display import HTML, display
-from IPython.core.magic import Magics, line_cell_magic, line_magic, magics_class
+from IPython.core.magic import (
+    Magics,
+    cell_magic,
+    line_cell_magic,
+    line_magic,
+    magics_class,
+)
 from IPython.core.magic_arguments import argument, magic_arguments, parse_argstring
 
 from sqlmesh.core import constants as c
@@ -32,7 +38,7 @@ def display(self) -> t.Callable:
         from sqlmesh import runtime_env
 
         if runtime_env.is_databricks:
-            # Use Databrick's special display instead of the normal IPython display
+            # Use Databricks' special display instead of the normal IPython display
             return self._shell.user_ns["display"]
         return display
 
@@ -271,7 +277,7 @@ def plan(self, line: str) -> None:
     )
     @argument("--start", "-s", type=str, help="Start date to evaluate.")
     @argument("--end", "-e", type=str, help="End date to evaluate.")
-    @argument("--skip-janitor", action="store_true", help="Skip the jantitor task.")
+    @argument("--skip-janitor", action="store_true", help="Skip the janitor task.")
     @line_magic
     def run_dag(self, line: str) -> None:
         """Evaluate the DAG of models using the built-in scheduler."""
@@ -349,7 +355,7 @@ def render(self, line: str) -> None:
         type=str,
         help="An optional variable name to store the resulting dataframe.",
     )
-    @line_cell_magic
+    @cell_magic
     def fetchdf(self, line: str, sql: str) -> None:
         """Fetches a dataframe from sql, optionally storing it in a variable."""
         args = parse_argstring(self.fetchdf, line)