fix(pacmak): go docs overview displays repeating description (#4081)

Our `go docs` have been broken since jsii `v1.65.0`. This was due to moving to emitting one file per type and headers being added to all those files: [Impacting PR](https://github.com/aws/jsii/pull/3698/files#diff-0a99c713a1282d6efe349c932d74dbfbdf1d926834c46ebfb5d65daeb27073f3R263)

The first occurrence was in [docs for cdk v2.39.0](https://pkg.go.dev/github.com/aws/aws-cdk-go/awscdk/v2@v2.39.0) and is still present in the [latest version](https://pkg.go.dev/github.com/aws/aws-cdk-go/awscdk/v2).

The header being added is `Version 2 of the AWS Cloud Development Kit library` to multiple files. It's determining this value from the [package.json](https://github.com/aws/aws-cdk/blob/main/packages/aws-cdk-lib/package.json#L4) file of `aws-cdk-lib`. I see adding this is most relevant for [maven](https://github.com/aws/jsii/blob/main/packages/jsii-reflect/lib/assembly.ts#L46-L52), hence removing it from `go` since I do not believe it's bringing much value to our documentation. Let me know if you feel otherwise :) 

---

By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

packages/codemaker/src/codemaker.ts

@@ -196,6 +196,14 @@ export class CodeMaker {
     return caseutils.toSnakeCase(s, sep);
   }
 
+  /**
+   * Gets currently opened file path.
+   * @returns Currently opened file path.
+   */
+  public getCurrentFilePath(): string | undefined {
+    return this.currentFile?.filePath;
+  }
+
   private makeIndent(): string {
     const length = this.currentIndentLength;
     if (length <= 0) {

packages/jsii-pacmak/lib/targets/go/package.ts

@@ -37,6 +37,7 @@ import { VersionFile } from './version-file';
 
 export const GOMOD_FILENAME = 'go.mod';
 export const GO_VERSION = '1.18';
+const MAIN_FILE = 'main.go';
 
 /*
  * Package represents a single `.go` source file within a package. This can be the root package file or a submodule
@@ -203,10 +204,9 @@ export abstract class Package {
     if (this.types.length > 0) {
       const { code } = context;
 
-      const initFile = join(this.directory, `main.go`);
+      const initFile = join(this.directory, MAIN_FILE);
       code.openFile(initFile);
-      code.line(`package ${this.packageName}`);
-      code.line();
+      this.emitHeader(code);
       importGoModules(code, [GO_REFLECT, JSII_RT_MODULE]);
       code.line();
       code.openBlock('func init()');
@@ -470,7 +470,12 @@ export class RootPackage extends Package {
   }
 
   protected emitHeader(code: CodeMaker) {
-    if (this.assembly.description !== '') {
+    const currentFilePath = code.getCurrentFilePath();
+    if (
+      this.assembly.description !== '' &&
+      currentFilePath !== undefined &&
+      currentFilePath.includes(MAIN_FILE)
+    ) {
       code.line(`// ${this.assembly.description}`);
     }
     code.line(`package ${this.packageName}`);