MINOR: Fix broken links in contrib guide (#3135)

* Replace relative URLs with absolute URLs when publishing the contributors guide

* add license

docs/.gitignore

@@ -16,4 +16,5 @@
 # under the License.
 
 build
+temp
 venv/

docs/README.md

@@ -17,7 +17,11 @@
   under the License.
 -->
 
-# DataFusion docs
+# DataFusion Documentation
+
+This folder contains the source content of the [User Guide](./source/user-guide)
+and [Contributor Guide](./source/contributor-guide). These are both published to
+https://arrow.apache.org/datafusion/ as part of the release process.
 
 ## Dependencies
 
@@ -27,19 +31,29 @@ inside a Python virtualenv.
 - Python
 - `pip install -r requirements.txt`
 
-## Build
+## Build & Preview
+
+Run the provided script to build the HTML pages.
+
+```bash
+./build.sh
+```
+
+The HTML will be generated into a `build` directory.
+
+Preview the site on Linux by running this command.
 
 ```bash
-make html
+firefox build/html/index.html
 ```
 
-## Release
+## Release Process
 
 The documentation is served through the
 [arrow-site](https://github.com/apache/arrow-site/) repo. To release a new
 version of the docs, follow these steps:
 
-1. Run `make html` inside `docs` folder to generate the docs website inside the `build/html` folder.
+1. Run `./build.sh` inside `docs` folder to generate the docs website inside the `build/html` folder.
 2. Clone the arrow-site repo
 3. Checkout to the `asf-site` branch (NOT `master`)
 4. Copy build artifacts into `arrow-site` repo's `datafusion` folder with a command such as

docs/build.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+set -e
+rm -rf build 2> /dev/null
+rm -rf temp 2> /dev/null
+mkdir temp
+cp -rf source/* temp/
+# replace relative URLs with absolute URLs
+sed -i 's/\.\.\/\.\.\/\.\.\//https:\/\/github.com\/apache\/arrow-datafusion\/blob\/master\//g' temp/contributor-guide/index.md
+make SOURCEDIR=`pwd`/temp html

docs/source/contributor-guide/index.md

@@ -154,7 +154,7 @@ Criterion integrates with Cargo's built-in [benchmark support](https://doc.rust-
 cargo bench --bench BENCHMARK_NAME
 ```
 
-A full list of benchmarks can be found [here](./datafusion/benches).
+A full list of benchmarks can be found [here](../../../datafusion/benches).
 
 _[cargo-criterion](https://github.com/bheisler/cargo-criterion) may also be used for more advanced reporting._
 
@@ -187,7 +187,7 @@ Below is a checklist of what you need to do to add a new scalar function to Data
   - [here](../../../datafusion/physical-expr/src/math_expressions.rs) for math functions
   - [here](../../../datafusion/physical-expr/src/datetime_expressions.rs) for datetime functions
   - create a new module [here](../../../datafusion/physical-expr/src) for other functions
-- In [core/src/physical_plan](datafusion/core/src/physical_plan/functions.rs), add:
+- In [core/src/physical_plan](../../../datafusion/core/src/physical_plan/functions.rs), add:
   - a new variant to `BuiltinScalarFunction`
   - a new entry to `FromStr` with the name of the function as called by SQL
   - a new line in `return_type` with the expected return type of the function, given an incoming type