docs: on append, overwrite, delete and z-ordering (#1897)

# Description

Adds docs on how to append, overwrite, delete rows, and Z Order Delta
tables.

Will add much more detailed pages in the future. Just getting the
high-level skeleton of the docs developed.

docs/usage/appending-overwriting-delta-lake-table.md

@@ -0,0 +1,78 @@
+# Appending to and overwriting a Delta Lake table
+
+This section explains how to append to an exising Delta table and how to overwrite a Delta table.
+
+## Delta Lake append transactions
+
+Suppose you have a Delta table with the following contents:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
+|     3 | c        |
++-------+----------+
+```
+
+Append two additional rows of data to the table:
+
+```python
+from deltalake import write_deltalake, DeltaTable
+
+df = pd.DataFrame({"num": [8, 9], "letter": ["dd", "ee"]})
+write_deltalake("tmp/some-table", df, mode="append")
+```
+
+Here are the updated contents of the Delta table:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
+|     3 | c        |
+|     8 | dd       |
+|     9 | ee       |
++-------+----------+
+```
+
+Now let's see how to perform an overwrite transaction.
+
+## Delta Lake overwrite transactions
+
+Now let's see how to overwrite the exisitng Delta table.
+
+```python
+df = pd.DataFrame({"num": [11, 22], "letter": ["aa", "bb"]})
+write_deltalake("tmp/some-table", df, mode="overwrite")
+```
+
+Here are the contents of the Delta table after the overwrite operation:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|    11 | aa       |
+|    22 | bb       |
++-------+----------+
+```
+
+Overwriting just performs a logical delete.  It doesn't physically remove the previous data from storage.  Time travel back to the previous version to confirm that the old version of the table is still accessable.
+
+```
+dt = DeltaTable("tmp/some-table", version=1)
+
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
+|     3 | c        |
+|     8 | dd       |
+|     9 | ee       |
++-------+----------+
+```

docs/usage/create-delta-lake-table.md

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+# Creating a Delta Lake Table
+
+This section explains how to create a Delta Lake table.
+
+You can easily write a DataFrame to a Delta table.
+
+```python
+from deltalake import write_deltalake
+import pandas as pd
+
+df = pd.DataFrame({"num": [1, 2, 3], "letter": ["a", "b", "c"]})
+write_deltalake("tmp/some-table", df)
+```
+
+Here are the contents of the Delta table in storage:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
+|     3 | c        |
++-------+----------+
+```

docs/usage/deleting-rows-from-delta-lake-table.md

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+# Deleting rows from a Delta Lake table
+
+This section explains how to delete rows from a Delta Lake table.
+
+Suppose you have the following Delta table with four rows:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
+|     3 | c        |
+|     4 | d        |
++-------+----------+
+```
+
+Here's how to delete all the rows where the `num` is greater than 2:
+
+```python
+dt = DeltaTable("tmp/my-table")
+dt.delete("num > 2")
+```
+
+Here are the contents of the Delta table after the delete operation has been performed:
+
+```
++-------+----------+
+|   num | letter   |
+|-------+----------|
+|     1 | a        |
+|     2 | b        |
++-------+----------+
+```

docs/usage/optimize/delta-lake-z-order.md

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+# Delta Lake Z Order
+
+This section explains how to Z Order a Delta table.
+
+Z Ordering colocates similar data in the same files, which allows for better file skipping and faster queries.
+
+Suppose you have a table with `first_name`, `age`, and `country` columns.
+
+If you Z Order the data by the `country` column, then individuals from the same country will be stored in the same files.  When you subquently query the data for individuals from a given country, it will execute faster because more data can be skipped.
+
+Here's how to Z Order a Delta table:
+
+```python
+dt = DeltaTable("tmp")
+dt.optimize.z_order([country])
+```

mkdocs.yml

@@ -19,12 +19,17 @@ nav:
   - Usage:
     - Installation: usage/installation.md
     - Overview: usage/index.md
-    - Loading a Delta Table: usage/loading-table.md
-    - Examining a Delta Table: usage/examining-table.md
-    - Querying a Delta Table: usage/querying-delta-tables.md
-    - Managing a Delta Table: usage/managing-tables.md
-    - Writing Delta Tables: usage/writing-delta-tables.md
-    - Small file compaction: usage/small-file-compaction-with-optimize.md
+    - Creating a table: usage/create-delta-lake-table.md
+    - Loading a table: usage/loading-table.md
+    - Append/overwrite tables: usage/appending-overwriting-delta-lake-table.md
+    - Examining a table: usage/examining-table.md
+    - Querying a table: usage/querying-delta-tables.md
+    - Managing a table: usage/managing-tables.md
+    - Writing a table: usage/writing-delta-tables.md
+    - Deleting rows from a table: usage/deleting-rows-from-delta-lake-table.md
+    - Optimize:
+      - Small file compaction: usage/optimize/small-file-compaction-with-optimize.md
+      - Z Order: usage/optimize/delta-lake-z-order.md
   - API Reference:
     - api/delta_table.md
     - api/schema.md