params: support for tracking all params in a file

content/docs/command-reference/params/index.md

@@ -43,7 +43,9 @@ to define [stage](/doc/command-reference/run) dependencies more granularly:
 changes to other parts of the params file will not affect the stage. Parameter
 dependencies also prevent situations where several stages share a regular
 dependency (e.g. a config file), and any change in it invalidates all of them
-(see `dvc status`), causing unnecessary re-executions upon `dvc repro`.
+(see `dvc status`), causing unnecessary re-executions upon `dvc repro`. However,
+you can track all the parameters in a file by setting _parameter value_ to be
+`null`.
 
 The default **parameters file** name is `params.yaml`, but any other YAML 1.2,
 JSON, TOML, or [Python](#examples-python-parameters-file) files can be used

content/docs/user-guide/project-structure/pipelines-files.md

@@ -51,8 +51,17 @@ If it writes files or dirs, they can be defined as <abbr>outputs</abbr>
 ### Parameter dependencies
 
 [Parameters](/doc/command-reference/params) are a special type of stage
-dependency. They consist of a name/value pair to find in a YAML, JSON, TOML, or
-Python parameters file (`params.yaml` by default). Example:
+dependency. They consist of a list of params to track in one of these formats:
+
+1. A param key/value pair that can be found in `params.yaml` (default params
+   file);
+2. A dictionary named by the file path to a custom params file, and with a list
+   of param key/value pairs to find in it;
+3. An empty set (give no value or use `null`) named by the file path to a params
+   file: to track all the params in it dynamically.
+
+> Note that file paths used must be to valid YAML, JSON, TOML, or Python
+> parameters file.
 
 ```yaml
 stages:
@@ -63,6 +72,9 @@ stages:
     params:
       - threshold
       - passes
+      - custom_params.yaml: # track only specified parameters
+          - epochs
+      - config.json: # track all parameters
     outs:
       - clean.txt
 ```