docs: fix typos and grammar errors in documentation (#8422)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: anthony bushong <agmsb@users.noreply.github.com>
Co-authored-by: Arya Gummadi <aryagummadi@google.com>

CONTRIBUTING.md

@@ -144,7 +144,7 @@ To start the Gemini CLI from the source code (after building), run the following
 npm start
 ```
 
-If you'd like to run the source build outside of the gemini-cli folder you can utilize `npm link path/to/gemini-cli/packages/cli` (see: [docs](https://docs.npmjs.com/cli/v9/commands/npm-link)) or `alias gemini="node path/to/gemini-cli/packages/cli"` to run with `gemini`
+If you'd like to run the source build outside of the gemini-cli folder, you can utilize `npm link path/to/gemini-cli/packages/cli` (see: [docs](https://docs.npmjs.com/cli/v9/commands/npm-link)) or `alias gemini="node path/to/gemini-cli/packages/cli"` to run with `gemini`
 
 ### Running Tests
 

docs/releases.md

@@ -29,7 +29,7 @@ npm install -g @google/gemini-cli@latest
 
 ### Nightly
 
-- New releases will be published each week at UTC 0000 each day, This will be all changes from the main branch as represted at time of release. It should be assumed there are pending validations and issues. Use `nightly` tag.
+- New releases will be published each day at UTC 0000. This will be all changes from the main branch as represented at time of release. It should be assumed there are pending validations and issues. Use `nightly` tag.
 
 ```bash
 npm install -g @google/gemini-cli@nightly

packages/a2a-server/development-extension-rfc.md

@@ -273,7 +273,7 @@ message DevelopmentToolEvent {
   // The tier of the user (optional).
   string user_tier = 3;
 
-  // An unexpected error occured in the agent execution (optional).
+  // An unexpected error occurred in the agent execution (optional).
   string error = 4;
 }
 ```