chore: remove squares braces from issue title templates

Author: jelbourn

.github/ISSUE_TEMPLATE/bug.md

@@ -1,7 +1,7 @@
 ---
 name: Bug Report
-title: "bug([COMPONENT]): [TITLE]"
-about: Report a bug found in Angular Material or the CDK
+title: "bug(COMPONENT): TITLE"
+about: Report a bug in Angular Material or the CDK
 labels: needs triage
 ---
 

.github/ISSUE_TEMPLATE/docs.md

@@ -1,6 +1,6 @@
 ---
 name: Documentation
-title: "docs-bug([COMPONENT]): [TITLE]"
+title: "docs-bug(COMPONENT): TITLE"
 about: Suggest an improvement to our documentation at material.angular.io
 labels: docs, needs triage
 ---

.github/ISSUE_TEMPLATE/feature.md

@@ -1,6 +1,6 @@
 ---
 name: Feature
-title: "fr([COMPONENT]): [TITLE]"
+title: "feat(COMPONENT): TITLE"
 about: Propose a new feature for Angular Material or the CDK
 labels: feature, needs triage
 ---

.github/ISSUE_TEMPLATE/troubleshooting.md

@@ -1,6 +1,6 @@
 ---
 name: Troubleshooting
-title: "help([COMPONENT]): [TITLE]"
+title: "help(COMPONENT): TITLE"
 about: Request for help on an issue you are facing with Angular Material or the CDK
 labels: troubleshooting, needs triage
 ---