README: Add update_conda_lock information

Signed-off-by: Adam Jeliński <[email protected]>

README.md

@@ -6,6 +6,34 @@ This repository contains [actions](https://docs.github.com/en/free-pro-team@late
 
 Runs license and python linting checks.
 
+✔️ [symbiflow/actions/update_conda_lock](update_conda_lock)
+
+Simplifies maintaining Conda Locks, i.e. stable Conda environment files with precise Conda and Pip package versions based on a given Conda environment file.
+
+Running this action creates a Pull Request that creates or updates a Conda Lock.
+Checking workflow results and merging the Pull Request are the only actions that require repository maintainer's attention.
+
+Please bear in mind that the Pull Request can only trigger workflows if this action is used with GitHub's [Personal Access Token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token).
+Always set such a token as [an encrypted secret](https://docs.github.com/en/actions/reference/encrypted-secrets) for security reasons.
+For example, after setting `NAME_OF_TOKEN_VAR` repository secret with *PAT*, use:
+```
+    steps:
+    - uses: symbiflow/actions/update_conda_lock@GIT_REVISION
+      with:
+        gh_access_token: ${{ secrets.NAME_OF_TOKEN_VAR }}
+```
+In case passing *PAT* is not an option, passing `secrets.GITHUB_TOKEN` will also result in creating a Pull Request but without triggering PR Checks.
+
+The inputs to this action are (bold ones are **required**):
+* `branch_name_core`: Name of the pushed branch; it will be suffixed with GH Action's Run ID.
+* `commit_message`: Message of the commit updating Conda Lock.
+* `conda_lock_file`: Path of the Conda Lock file (needs to have txt/yml/yaml extension).
+* `environment_file`: Path of the base `environment.yml` file.
+* **`gh_access_token`**: GitHub Access Token; use Personal Access Token to trigger workflows when issuing the Pull Request.
+* `pr_title_core`: Title of the Pull Request; it will be suffixed with UTC time and date.
+* `user_email`: Email address of the user creating commit.
+* `user_name`: Name of the user creating commit.
+
 # Examples
 
 These are examples of using "includable" workflows. Put these in