docs: use consistent bold formatting for list items

Author: zimeg

README.md

@@ -4,4 +4,4 @@ This collections of examples highlights features of a Slack app in the language
 
 ## Available demonstration
 
-- [Block Kit](./block-kit): the framework of visual components arranged to create app layouts.
+- **[Block Kit](./block-kit)**: The framework of visual components arranged to create app layouts.

block-kit/README.md

@@ -8,7 +8,7 @@ Read the [docs](https://docs.slack.dev/block-kit/) to learn concepts behind thes
 
 ### Blocks
 
-- **[Actions block](https://docs.slack.dev/reference/block-kit/blocks/actions-block)**: Holds multiple interactive elements. [Implementation](./src/main/java/blocks/Actions.java).
+- **[Actions](https://docs.slack.dev/reference/block-kit/blocks/actions-block)**: Holds multiple interactive elements. [Implementation](./src/main/java/blocks/Actions.java).
 - **[Context](https://docs.slack.dev/reference/block-kit/blocks/context-block)**: Provides contextual info, which can include both images and text. [Implementation](./src/main/java/blocks/Context.java).
 - **[Divider](https://docs.slack.dev/reference/block-kit/blocks/divider-block)**: Visually separates pieces of info inside of a message. [Implementation](./src/main/java/blocks/Divider.java).
 - **[File](https://docs.slack.dev/reference/block-kit/blocks/file-block)**: Displays info about remote files. [Implementation](./src/main/java/blocks/File.java).