Change "Get Involved" title to "Training"

[bethanyios]

Describe the solution you'd like

• [x] Change the "Get Involved" page title to "Training"
• [x] Change in navbar too
• [x] Change the url
• [x] Change the events tab title to "Conferences"
• [x] Careers tab is going to move to its own page https://github.com/yalla-coop/chiltern-website/issues/83

URL https://www.chilternmusictherapy.co.uk/get-involved

Additional context Full list of changes for context can be found here https://docs.google.com/document/d/1tNeTV5Hm9qvZatG69QTrI0eGMOGY80PUo-4PWlKj3qE/edit

Team - do not edit @thejoefriel @fadeomar @@Israa91

[fadeomar]

Development estimation: <0.5 days

[fadeomar]

hey @katieshuster , this is done and can be tested

[katieshuster]

That's great, thanks @fadeomar