docs: added changesets for core

.changeset/loud-files-do.md

+---
+"llamaindex": patch
+---
+
+Use compromise as sentence tokenizer

.changeset/moody-berries-reflect.md

+---
+"llamaindex": patch
+---
+
+Removed pdf-parse, and directly use latest pdf.js

.changeset/small-paws-sneeze.md

+---
+"llamaindex": patch
+---
+
+Added pinecone vector DB

CONTRIBUTING.md

@@ -8,7 +8,7 @@ Right now there are two packages of importance:
 
 packages/core which is the main NPM library llamaindex
 
-apps/simple is where the demo code lives
+examples is where the demo code lives
 
 ### Turborepo docs
 
@@ -47,7 +47,7 @@ We use Jest https://jestjs.io/ to write our test cases. Jest comes with a bunch
 
 ### Demo applications
 
-There is an existing ["simple"](/apps/simple/README.md) demos folder with mainly NodeJS scripts. Feel free to add additional demos to that folder. If you would like to try out your changes in the core package with a new demo, you need to run the build command in the README.
+There is an existing ["example"](/examples/README.md) demos folder with mainly NodeJS scripts. Feel free to add additional demos to that folder. If you would like to try out your changes in the core package with a new demo, you need to run the build command in the README.
 
 You can create new demo applications in the apps folder. Just run pnpm init in the folder after you create it to create its own package.json
 
@@ -56,7 +56,7 @@ You can create new demo applications in the apps folder. Just run pnpm init in t
 To install packages for a specific package or demo application, run
 
 ```
-pnpm add [NPM Package] --filter [package or application i.e. core or simple]
+pnpm add [NPM Package] --filter [package or application i.e. core or docs]
 ```
 
 To install packages for every package or application run