Mention about yarn upgrade for starting errors (#4069)

- also clean up markdown

docs/README.md

@@ -4,9 +4,11 @@ How to build these docs
 We use [Docusaurus 2](https://v2.docusaurus.io/) for our docs, a modern static website generator.
 
 ### Requirements
+
 Assuming you have [Node.js](https://nodejs.org/en/download/) installed (which includes npm), you can install Docusaurus with:
 
 You will need to install [Yarn](https://yarnpkg.com/getting-started/install) before you can build the site.
+
 ```sh
 npm install -g yarn
 ```
@@ -26,14 +28,36 @@ yarn
 yarn start
 ```
 
-This command starts a local development server and opens up a browser window. Usually at the URL http://localhost:3000
+This command starts a local development server and opens up a browser window. Usually at the URL <http://localhost:3000>
 Most changes are reflected live without having to restart the server.
 
+If you get an error starting yarn mentioning `update.latest` such as
+
+```sh
+>yarn start
+
+if (notifier.update && semver.gt(this.update.latest, this.update.current)) {
+TypeError: Cannot read property 'latest' of undefined
+    at Object.<anonymous> (E:\GitHubRepos\OpenRefine\docs\node_modules\@docusaurus\core\bin\docusaurus.js:49:46)
+error Command failed with exit code 1.
+```
+
+then it is likely that you will need to first run
+
+```sh
+yarn upgrade
+```
+
+which will update all dependencies and store them in the `yarn.lock` file to also be committed.
+
 ### Next version of OpenRefine docs
+
 If you wish to work on the next version of docs for OpenRefine (`master` branch) then you will need to:
+
 1. Git checkout our `master` branch
 2. Edit files under `docs/docs/`
-3. Preview changes with the URL kept pointing to http://localhost:3000/next which will automatically show changes live with yarn after you save a file.
+3. Preview changes with the URL kept pointing to <http://localhost:3000/next> which will automatically
+   show changes live with yarn after you save a file.
 
 ### Build
 
@@ -49,19 +73,22 @@ This command generates static content into the `build` directory and can be serv
 GIT_USER=<Your GitHub username> USE_SSH=true yarn deploy
 ```
 
-If you are using GitHub pages for hosting, this command is a convenient way to build the website and push to the `gh-pages` branch.
+If you are using GitHub pages for hosting, this command is a convenient way to build the website
+and push to the `gh-pages` branch.
 
 ### Translations
 
 It is now possible to translate the [OpenRefine docs](https://docs.openrefine.org/) via the
 Crowdin platform:
 
-https://crowdin.com/project/openrefine
+<https://crowdin.com/project/openrefine>
 
 Unfortunately, unlike Weblate, we need to manually invite anyone who
 wants to contribute translations. Feel free to request an invite by emailing us at openrefine-dev@googlegroups.com
 We can also add languages, depending on interest.
 
-Your translations will not be immediately published on https://docs.openrefine.org, it will take a few days (at the next commit on the master branch) and the translated pages will first appear under https://docs.openrefine.org/next/ (the documentation for the development version).
+Your translations will not be immediately published on <https://docs.openrefine.org>, it will take a few days
+(at the next commit on the master branch).
+The translated pages will first appear under <https://docs.openrefine.org/next/> (the documentation for the development version).
 When we publish a version, the translations for that version, we will take a snapshot of the translations during that time.
 We will trial this process for 3.5.