[doc] symlink the doc dependency lock file (#58520)

and ask people to use that lock file for building docs.

Signed-off-by: Lonnie Liu <lonnie@anyscale.com>

Author: aslonnie

.readthedocs.yaml

@@ -20,4 +20,4 @@ sphinx:
 # https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
 python:
   install:
-    - requirements: python/deplocks/docs/docbuild_depset_py3.10.lock
+    - requirements: doc/requirements-doc.lock.txt

doc/README.md

@@ -8,7 +8,7 @@ To build the documentation, make sure you have `ray` installed first.
 For building the documentation locally install the following dependencies:
 
 ```bash
-pip install -r requirements-doc.txt
+pip install -r requirements-doc.lock.txt
 ```
 
 ## Building the documentation

doc/requirements-doc.lock.txt

@@ -0,0 +1 @@
+../python/deplocks/docs/docbuild_depset_py3.10.lock

doc/source/ray-contribute/docs.md

@@ -50,10 +50,10 @@ conda activate docs
 Install the documentation dependencies with the following command:
 
 ```shell
-pip install -r requirements-doc.txt
+pip install -r requirements-doc.lock.txt
 ```
 
-Don't use `-U` in this step. You don't want to upgrade dependencies because `requirements-doc.txt` pins exact versions you need to build the docs.
+Don't use `-U` in this step; `requirements-doc.lock.txt` is a lock file that pins the exact versions of all the required dependencies.
 
 ### Build documentation
 Before building, clean your environment first by running: