Add docs code testing & documentation syntax changes (#196)

- Creates testing files `md_testing.py` and `md_testing.js` for testing
python and nodejs code in markdown files in the documentation
This listens for HTML tags as well: `<!--[language] code code
code...-->` will create a set-up file to create some mock tables or to
fulfill some assumptions in the documentation.
- Creates a github action workflow that triggers every push/pr to
`docs/**`
- Modifies documentation so tests run (mostly indentation, some small
syntax errors and some missing imports)

A list of excluded files that we need to take a closer look at later on:
```javascript
const excludedFiles = [
  "../src/fts.md",
  "../src/embedding.md",
  "../src/examples/serverless_lancedb_with_s3_and_lambda.md",
  "../src/examples/serverless_qa_bot_with_modal_and_langchain.md",
  "../src/examples/youtube_transcript_bot_with_nodejs.md",
];
```
Many of them can't be done because we need the OpenAI API key :(.
`fts.md` has some issues with the library, I believe this is still
experimental?

Closes #170

---------

Co-authored-by: Will Jones <willjones127@gmail.com>

docs/src/javascript/README.md

@@ -16,9 +16,11 @@ npm install vectordb
 
 ```javascript
 const lancedb = require('vectordb');
-const db = lancedb.connect('<PATH_TO_LANCEDB_DATASET>');
-const table = await db.openTable('my_table');
-const query = await table.search([0.1, 0.3]).limit(20).execute();
+const db = await lancedb.connect('data/sample-lancedb');
+const table = await db.createTable("my_table", 
+      [{ id: 1, vector: [0.1, 1.0], item: "foo", price: 10.0 },
+      { id: 2, vector: [3.9, 0.5], item: "bar", price: 20.0 }])
+const results = await table.search([0.1, 0.3]).limit(20).execute();
 console.log(results);
 ```