[PATCH] security-manual: some grammar and wording fixes in intro

Tweaks:

  - grammar
  - punctuation
  - delete word "necessary" as that is too strong a word and implies
    that what is being discussed is mandatory when it isn't

Signed-off-by: Robert P. J. Day <[email protected]>

---

diff --git a/documentation/security-manual/intro.rst b/documentation/security-manual/intro.rst
index 03a8ed1ca..5ea6f5110 100644
--- a/documentation/security-manual/intro.rst
+++ b/documentation/security-manual/intro.rst
@@ -5,24 +5,24 @@ Introduction
 ************

 Welcome to the Yocto Project Security Manual. This manual provides relevant
-procedures necessary for dealing with security-related tasks supported in the
+procedures for dealing with security-related tasks supported in the
 Yocto Project environment. This manual groups related procedures into
 higher-level sections. Procedures can consist of high-level steps or low-level
 steps depending on the topic.

 This manual provides the following:

--  Procedures that help you securing an image with features supported by the
-   Yocto Project; for example making a root filesystem read-only.
+-  Procedures that help you secure an image using features supported by the
+   Yocto Project; for example, making a root filesystem read-only.

--  Procedures related to processes outside of the target images; for example how
+-  Procedures related to processes outside of the target images; for example, how
    to deal with vulnerabilities.

 This manual does not provide the following:

--  Procedures on security features implemented outside of
+-  Procedures for security features implemented outside of
    :term:`OpenEmbedded-Core (OE-Core)`.

--  Documentation on the security mechanisms themselves, which can often be found
+-  Documentation for the security mechanisms themselves, which can often be found
    in the documentation of the feature itself. This manual focuses on how to
-   integrate the security mechanism within the Yocto Project.
+   integrate those security mechanisms within the Yocto Project.