fix typos in flowchart page

[TunrayoIlawole]

fixed typo: Flowchart

Fixes #163

Short description of what this resolves:

It corrects some typos on the flowchart lesson page

What Changes proposed in this pull request:

• Spelling and grammar correction

Checklist

• [x] Added description of change
• [x] Relevant documentation/comments is changed or added
• [x] PR title follows semantic commit guidelines
• [x] Search previous suggestions before making a new one, as yours may be a duplicate.
• [x] I acknowledge that all my contributions will be made under the project's license.

Notes: