docs: clarify context parameter is optional in all form method docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: DavertMik

docs/webapi/appendField.mustache

@@ -1,7 +1,7 @@
 Appends text to a input field or textarea.
 Field is located by name, label, CSS or XPath
 
-The third parameter is a context (CSS or XPath locator) to narrow the search.
+The third parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.appendField('#myTextField', 'appended');

docs/webapi/attachFile.mustache

@@ -2,7 +2,7 @@ Attaches a file to element located by label, name, CSS or XPath
 Path to file is relative current codecept directory (where codecept.conf.ts or codecept.conf.js is located).
 File will be uploaded to remote system (if tests are running remotely).
 
-The third parameter is a context (CSS or XPath locator) to narrow the search.
+The third parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.attachFile('Avatar', 'data/avatar.jpg');

docs/webapi/checkOption.mustache

@@ -1,7 +1,7 @@
 Selects a checkbox or radio button.
 Element is located by label or name or CSS or XPath.
 
-The second parameter is a context (CSS or XPath locator) to narrow the search.
+The second parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.checkOption('#agree');

docs/webapi/clearField.mustache

@@ -1,6 +1,6 @@
 Clears a `<textarea>` or text `<input>` element's value.
 
-The second parameter is a context (CSS or XPath locator) to narrow the search.
+The second parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.clearField('Email');

docs/webapi/fillField.mustache

@@ -1,7 +1,7 @@
 Fills a text field or textarea, after clearing its value, with the given string.
 Field is located by name, label, CSS, or XPath.
 
-The third parameter is a context (CSS or XPath locator) to narrow the search.
+The third parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 // by label

docs/webapi/selectOption.mustache

@@ -2,7 +2,7 @@ Selects an option in a drop-down select.
 Field is searched by label | name | CSS | XPath.
 Option is selected by visible text or by value.
 
-The third parameter is a context (CSS or XPath locator) to narrow the search.
+The third parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.selectOption('Choose Plan', 'Monthly'); // select by label

docs/webapi/uncheckOption.mustache

@@ -1,7 +1,7 @@
 Unselects a checkbox or radio button.
 Element is located by label or name or CSS or XPath.
 
-The second parameter is a context (CSS or XPath locator) to narrow the search.
+The second parameter is an optional context (CSS or XPath locator) to narrow the search.
 
 ```js
 I.uncheckOption('#agree');