Fix the use of the #Visiting-External-Sites anchor

The existing links to #Visiting-external-sites will not function
properly, as the capitalization does not match the header. This change
updates several existing anchor references.

Author: rick-a-lane-ii

docs/faq/questions/using-cypress-faq.mdx

@@ -665,7 +665,7 @@ For further detail see the
 
 Don't try to use your UI to check email. Instead opt to programmatically use 3rd
 party APIs or talk directly to your server. Read about this
-[best practice](/guides/references/best-practices#Visiting-external-sites) here.
+[best practice](/guides/references/best-practices#Visiting-External-Sites) here.
 
 :::
 

docs/guides/guides/cross-origin-testing.mdx

@@ -129,7 +129,7 @@ than your superdomain, which can be safely tested with
 
 We've written several other guides specifically about handling this situation.
 
-- [Best Practices: Visiting external sites](/guides/references/best-practices#Visiting-external-sites)
+- [Best Practices: Visiting external sites](/guides/references/best-practices#Visiting-External-Sites)
 - [Web Security: Common Workarounds](/guides/guides/web-security#Common-Workarounds)
 - [Recipes: Logging In - Single Sign On](/examples/recipes#Logging-In)
 - [Guides: Amazon Cognito Authentication](/guides/end-to-end-testing/amazon-cognito-authentication)

docs/guides/guides/web-security.mdx

@@ -226,7 +226,7 @@ cy.get('selector').should('exist') // Cypress errors
 
 We do not recommend visiting a superdomain that you don't control in your tests
 which you can read more about
-[here](/guides/references/best-practices#Visiting-external-sites)
+[here](/guides/references/best-practices#Visiting-External-Sites)
 
 However, if you control this superdomain, either by owning the hosted instance
 or by other means, we recommend testing this superdomain with `cy.origin`.
@@ -395,7 +395,7 @@ cy.origin('http://some.superdomain.com', () => {
 Sometimes, when using `cy.origin` and especially with websites that are not
 under your immediate test control, cross-origin errors may still tend to creep
 up. We don't recommend visiting or interacting with sites you
-[do not control](/guides/references/best-practices#Visiting-external-sites).
+[do not control](/guides/references/best-practices#Visiting-External-Sites).
 However, if this is necessary, most of these issues can usually be remedied by
 applying` the
 [modify obstructive third-party code](/guides/references/experiments#Configuration)