Add glossary definitions for code fixes (#6190)

Fixes #6177

src/_data/glossary.yml

@@ -1,3 +1,21 @@
+- term: "Assist"
+  short_description: |-
+    An automated, local code edit targeted at making common improvements to code.
+  long_description: |-
+    An assist is an automated, local code edit targeted at making common
+    improvements to code.
+    Examples of assists include converting `switch` statements to `switch`
+    expressions, reversing the `then` and `else` blocks in an `if` statement,
+    and inserting widgets into a widget structure.
+  related_links:
+    - text: "Refactor"
+      link: "#refactor"
+  labels:
+    - "tools"
+    - "analyzer"
+  alternate:
+    - "Quick assist"
+
 - term: "Constant context"
   short_description: |-
     A region of code where the const keyword is implied and
@@ -371,6 +389,36 @@
     - "language"
     - "libraries"
 
+- term: "Quick fix"
+  short_description: |-
+    An automated, local code edit targeted at fixing the issue reported by a
+    specific diagnostic.
+  related_links:
+    - text: "Quick fixes for analysis issues"
+      link: "https://medium.com/dartlang/quick-fixes-for-analysis-issues-c10df084971a"
+    - text: "Diagnostic messages"
+      link: "/tools/diagnostic-messages"
+    - text: "Linter rules"
+      link: "/tools/linter-rules"
+  labels:
+    - "tools"
+    - "understanding diagnostics"
+
+- term: "Refactor"
+  short_description: |-
+    A code edit targeted at modifications that are either non-local or that
+    require user interaction.
+  long_description: |-
+    A refactor is a code edit targeted at modifications that are either non-local
+    or that require user interaction.
+    Examples of refactors include renaming, removing, or extracting code.
+  related_links:
+    - text: "Assist"
+      link: "#assist"
+  labels:
+    - "tools"
+    - "analysis"
+
 - term: "Refutable pattern"
   short_description: |-
     A pattern that can be tested against a value.

src/content/resources/glossary.md

@@ -4,6 +4,10 @@ description: A glossary reference for terminology used across dart.dev.
 body_class: glossary-page
 ---
 
+{% comment %}
+  Write glossary entries into the src/_data/glossary.yml file.
+{% endcomment -%}
+
 The following are definitions of terms used across the Dart documentation.
 
 {% assign sorted_terms = glossary | sort: "term" %}