Added Hubspot to company list

[niranjan-kurhade]

Added HubSpot to the list. This is a modified version of, and should adhere to, the Contributing Guidelines.

• [ ] This PR contains housekeeping only (URL edits, copy changes etc) - if this is checked, delete other lines that don't apply
• [ ] You are an employee of the company mentioned and confirm all included details are correct.
• [ ] You know your alphabet - company is listed in alphabetical order in the README.md file.
• [ ] The company directly hires employees. No bootcamps / freelance sites / etc
• [ ] The company hires remote employees, or positions are available to remote workers and are clearly illustrated as such.
• [ ] A company profile is included - This is required for new additions.
• [ ] An entry has been added or edited within the readme.md file.
• [ ] Remote status has details regarding how the culture includes remote employees, how the company integrated remote workers, etc
• [ ] Region details the geographic regions in which this company employees can reside. For more details see the instructions in the example company profile.
• [ ] How to apply details the best approach for new applications, page on site where open position are listed, and any other help available for job hunters

[dougaitken]

@niranjan-kurhade although you didn't complete the Pull Request checklist at all, I'll allow it this time.