A corporate governance plan is not one of the types of documents that a company is required to file by the SEC or by state corporation regulators. Most governance plans are more in the nature of policies or guidelines, indicating how the company's management intends to run the company.
Sometimes a company adopts a corporate governance plan in response to pressure from institutional shareholders or to settle an investor class action lawsuit. Some companies adopt a plan because good ethics and transparency are a part of their image. Such plans can be found in the Investor Relations sections of the company's web site and would be discussed in the Management Discussion section of the company's Annual Report (SEC Form 10-K).
The rules actually binding on a company with respect to the nomination of officers and directors and their duties are in the company's articles of incorporation and bylaws. (SEC Exhibit 3.) The salary and compensation of executives is found in the company's Annual Reports (SEC Form 10K), quarterly reports (SEC Form 10-Q), and in proxy statements.
Bloomberg BNA also publishes some helpful resources for covering institutional investors' attempts to get companies to adopt specific measures for shareholder input, transparency, independent directors, socially responsible conduct, and so on.