Add small improvements to the Webpacker guide
Add small improvements to the Webpacker guide

- fix typos like double spaces, accidental caps
- improve some HTML links by giving them a label
- etc

Edouard-chin/rails,betesh/rails,Envek/rails,yawboakye/rails,Edouard-chin/rails,georgeclaghorn/rails,esparta/rails,esparta/rails,rails/rails,yahonda/rails,yawboakye/rails,joonyou/rails,yawboakye/rails,rails/rails,Envek/rails,kddeisz/rails,bogdanvlviv/rails,esparta/rails,bogdanvlviv/rails,BlakeWilliams/rails,joonyou/rails,Stellenticket/rails,bogdanvlviv/rails,Vasfed/rails,georgeclaghorn/rails,Edouard-chin/rails,Stellenticket/rails,MSP-Greg/rails,yahonda/rails,joonyou/rails,Erol/rails,Erol/rails,kmcphillips/rails,Vasfed/rails,betesh/rails,lcreid/rails,Erol/rails,esparta/rails,EmmaB/rails-1,yawboakye/rails,kmcphillips/rails,georgeclaghorn/rails,kmcphillips/rails,Envek/rails,rails/rails,Stellenticket/rails,rails/rails,georgeclaghorn/rails,lcreid/rails,yahonda/rails,kmcphillips/rails,joonyou/rails,MSP-Greg/rails,Erol/rails,kddeisz/rails,EmmaB/rails-1,lcreid/rails,Envek/rails,BlakeWilliams/rails,betesh/rails,BlakeWilliams/rails,kddeisz/rails,MSP-Greg/rails,EmmaB/rails-1,Vasfed/rails,lcreid/rails,bogdanvlviv/rails,betesh/rails,Stellenticket/rails,kddeisz/rails,BlakeWilliams/rails,MSP-Greg/rails,Vasfed/rails,Edouard-chin/rails,yahonda/rails