Fixed #swift-evolution menu item and 4 more links

This commit fixes 4 more broken links: the navigation menu item,
the reference-less link, and two other blog posts.

The `_navigation.yml` and several pages linked to
`/contributing/#evolution-process`, and we had an `<a>` tag with
`name="evolution-process"`, which is invalid in `htmlproofer`s eyes
because it's a link that does not have a reference.

Jekyll makes `id`s for every heading automatically, and we have
`/contributing/#swift-evolution` that we should link to instead.

Author: natikgadzhi

_data/navigation.yml

@@ -199,7 +199,7 @@
         - title: Blog Post Contributions
           name: website-and-blog-post-contributions
         - title: Swift Evolution
-          name: evolution-process
+          name: swift-evolution
         - title: Good First Issues
           name: good-first-issues
         - title: Contributing Code

_posts/2015-12-03-swift-3-api-design.md

@@ -73,5 +73,5 @@ list](/community/#swift-evolution).
 [clang-importer-proposal]: https://github.com/apple/swift-evolution/blob/master/proposals/0005-objective-c-name-translation.md  "Better Translation of Objective-C APIs into Swift proposal"
 [swift-3-api-guidelines-repo]: https://github.com/apple/swift-3-api-guidelines-review  "Swift 3 API Design Guidelines review repository"
 [objc-cocoa-guidelines]: https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/CodingGuidelines/CodingGuidelines.html  "Objective-C Coding Guidelines for Cocoa"
-[swift-evolution]: /contributing/#evolution-process  "Swift evolution process"
+[swift-evolution]: /contributing/#swift-evolution  "Swift evolution process"
 [core-libraries]: /core-libraries  "Swift core libraries"

_posts/2015-12-03-welcome.md

@@ -40,7 +40,7 @@ This website is the home of the Swift project with links to the resources you wi
 * The [Swift mailing lists](/community/#mailing-lists) are how we interact
 * The [Getting Started](/getting-started/) pages will help you setup a Swift development environment
 * The [Download](/download/) page includes pre-built binaries for the supported platforms
-* The [Swift Evolution Process](/contributing/#evolution-process) describes how new features are proposed
+* The [Swift Evolution Process](/contributing/#swift-evolution) describes how new features are proposed
 
 
 Welcome to the open source Swift community.

community/index.md

@@ -59,7 +59,7 @@ The current Core Team members are:
 
 [Contact via Forums](https://forums.swift.org/new-message?groupname=language-workgroup)
 
-The Language Steering Group comprises experts that the Swift Project Lead and the Core Team have identified as possessing a balance of perspectives and expertise to review, guide, and strategically align changes to the language mindfully.  The Language Steering Group reviews and helps iterate [language evolution proposals](/contributing/#evolution-process) from the community, acting as the approver of these proposals.  Workgroup members help drive the Swift language forward coherently to create the best possible general-purpose programming language.  The Language Steering Group membership is expected to change over time.
+The Language Steering Group comprises experts that the Swift Project Lead and the Core Team have identified as possessing a balance of perspectives and expertise to review, guide, and strategically align changes to the language mindfully.  The Language Steering Group reviews and helps iterate [language evolution proposals](/contributing/#swift-evolution) from the community, acting as the approver of these proposals.  Workgroup members help drive the Swift language forward coherently to create the best possible general-purpose programming language.  The Language Steering Group membership is expected to change over time.
 
 The current Language Steering Group members are:
 

contributing/_swift-evolution-process.md

@@ -1,5 +1,3 @@
-<a name="evolution-process"></a>
-
 ## Swift Evolution
 
 Shaping the future of Swift is a community effort that anyone can participate in via the [Evolution section of the Swift forums][swift-evolution-forums].