Update docs/ with params/results syntax changes

docs/tasks.md

@@ -449,10 +449,10 @@ You can specify parameters, such as compilation flags or artifact names, that yo
 
 Parameter names:
 
-- Must only contain alphanumeric characters, hyphens (`-`), and underscores (`_`).
+- Must only contain alphanumeric characters, hyphens (`-`), underscores (`_`), and dots (`.`).
 - Must begin with a letter or an underscore (`_`).
 
-For example, `fooIs-Bar_` is a valid parameter name, but `barIsBa$` or `0banana` are not.
+For example, `foo.Is-Bar_` is a valid parameter name, but `barIsBa$` or `0banana` are not.
 
 Each declared parameter has a `type` field, which can be set to either `array` or `string`. `array` is useful in cases where the number
 of compilation flags being supplied to a task varies throughout the `Task's` execution. If not specified, the `type` field defaults to
@@ -478,7 +478,14 @@ spec:
   steps:
     - name: build
       image: my-builder
-      args: ["build", "$(params.flags[*])", "url=$(params.someURL)"]
+      args: [
+        "build",
+        "$(params.flags[*])",
+        # It would be equivalent to use $(params["someURL"]) here,
+        # which is necessary when the parameter name contains '.'
+        # characters (e.g. `$(params["some.other.URL"])`)
+        'url=$(params.someURL)',
+      ]
 ```
 
 The following `TaskRun` supplies a dynamic number of strings within the `flags` parameter:
@@ -790,6 +797,8 @@ variable values as follows:
 - To reference a parameter in a `Task`, use the following syntax, where `<name>` is the name of the parameter:
   ```shell
   $(params.<name>)
+  # or subscript form:
+  $(params["<name>"])
   ```
 - To access parameter values from resources, see [variable substitution](resources.md#variable-substitution)
 

docs/variables.md

@@ -17,7 +17,9 @@ For instructions on using variable substitutions see the relevant section of [th
 | Variable | Description |
 | -------- | ----------- |
 | `params.<param name>` | The value of the parameter at runtime. |
+| `params["<param name>"]` | (see above) |
 | `tasks.<taskName>.results.<resultName>` | The value of the `Task's` result. Can alter `Task` execution order within a `Pipeline`.) |
+| `tasks.<taskName>.results["<resultName>"]` | (see above)) |
 | `workspaces.<workspaceName>.bound` | Whether a `Workspace` has been bound or not. "false" if the `Workspace` declaration has `optional: true` and the Workspace binding was omitted by the PipelineRun. |
 | `context.pipelineRun.name` | The name of the `PipelineRun` that this `Pipeline` is running in. |
 | `context.pipelineRun.namespace` | The namespace of the `PipelineRun` that this `Pipeline` is running in. |
@@ -32,9 +34,11 @@ For instructions on using variable substitutions see the relevant section of [th
 | Variable | Description |
 | -------- | ----------- |
 | `params.<param name>` | The value of the parameter at runtime. |
+| `params["<param name>"]` | (see above) |
 | `resources.inputs.<resourceName>.path` | The path to the input resource's directory. |
 | `resources.outputs.<resourceName>.path` | The path to the output resource's directory. |
 | `results.<resultName>.path` | The path to the file where the `Task` writes its results data. |
+| `results["<resultName>"].path` | (see above) |
 | `workspaces.<workspaceName>.path` | The path to the mounted `Workspace`. Empty string if an optional `Workspace` has not been provided by the TaskRun. |
 | `workspaces.<workspaceName>.bound` | Whether a `Workspace` has been bound or not. "false" if an optional`Workspace` has not been provided by the TaskRun. |
 | `workspaces.<workspaceName>.claim` | The name of the `PersistentVolumeClaim` specified as a volume source for the `Workspace`. Empty string for other volume types. |