Change "Got inspired" to "Inspired by GitLab".

This changes a few things to be more descriptive, grammatically pleasing, and search-engine friendly, including the following:

• "Got inspired" → "Inspired by GitLab"
• "Companies that got inspired by GitLab's culture and/or GitLab's Handbook" → "Inspired by GitLab"
• "List of companies that got inspired by GitLab" → "Companies that have been inspired by GitLab"
• https://about.gitlab.com/handbook/got-inspired/ → https://about.gitlab.com/handbook/inspired-by-gitlab/

This includes a forwarder from the old URL to the new one, but the following pages have links that will need to be updated separately:

• https://about.gitlab.com/company/culture/all-remote/
• https://about.gitlab.com/2019/06/28/five-things-you-hear-from-gitlab-ceo/ - updated in !29963 (merged)

cc @dmurph