refactor(material/schematics): fix some typos and add JSDoc

Author: Splaktar

src/material/schematics/ng-generate/theming-api/migration.ts

@@ -91,7 +91,7 @@ function detectImports(content: string, prefix: string): {imports: string[], nam
   return {imports, namespaces};
 }
 
-/** Migrates the Material symbls in a file. */
+/** Migrates the Material symbols in a file. */
 function migrateMaterialSymbols(content: string, importPath: string, namespaces: string[]): string {
   const initialContent = content;
   const namespace = 'mat';
@@ -142,6 +142,7 @@ function migrateCdkSymbols(content: string, importPath: string, namespaces: stri
  * Renames all Sass symbols in a file based on a pre-defined mapping.
  * @param content Content of a file to be migrated.
  * @param mapping Mapping between symbol names and their replacements.
+ * @param namespaces Names to iterate over and pass to getKeyPattern.
  * @param getKeyPattern Function used to turn each of the keys into a regex.
  * @param formatValue Formats the value that will replace any matches of the pattern returned by
  *  `getKeyPattern`.
@@ -183,15 +184,15 @@ function insertUseStatement(content: string, importPath: string, namespace: stri
 /** Formats a migration key as a Sass mixin invocation. */
 function mixinKeyFormatter(namespace: string|null, name: string): RegExp {
   // Note that adding a `(` at the end of the pattern would be more accurate, but mixin
-  // invocations don't necessarily have to include the parantheses. We could add `[(;]`,
+  // invocations don't necessarily have to include the parentheses. We could add `[(;]`,
   // but then we won't know which character to include in the replacement string.
   return new RegExp(`@include +${escapeRegExp((namespace ? namespace + '.' : '') + name)}`, 'g');
 }
 
 /** Returns a function that can be used to format a Sass mixin replacement. */
 function getMixinValueFormatter(namespace: string): (name: string) => string {
   // Note that adding a `(` at the end of the pattern would be more accurate,
-  // but mixin invocations don't necessarily have to include the parantheses.
+  // but mixin invocations don't necessarily have to include the parentheses.
   return name => `@include ${namespace}.${name}`;
 }