Docs: Updated the introductory readme.

This patch introduces minor changes to the readme page,
updating the content to align with the latest PSA
branding guidelines

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
Change-Id: I2ef03e646bb046de0f3dd81381244aa347298fb2
diff --git a/docs/introduction/readme.rst b/docs/introduction/readme.rst
index 213af41..55fdd5b 100644
--- a/docs/introduction/readme.rst
+++ b/docs/introduction/readme.rst
@@ -4,10 +4,9 @@
 
 Trusted Firmware-M (TF-M) implements the Secure Processing Environment (SPE)
 for Armv8-M, Armv8.1-M architectures (e.g. the `Cortex-M33`_, `Cortex-M23`_,
-`Cortex-M55`_ processors) or dual-core platforms.
-It is the Platform Security Architecture (PSA) reference implementation
-aligning with `PSA Certified`_ guidelines, enabling chips,
-Real Time Operating Systems and devices to become PSA Certified.
+`Cortex-M55`_ processors) or dual-core platforms.It is the platform security
+architecture  reference implementation aligning with PSA Certified guidelines,
+enabling chips,Real Time Operating Systems and devices to become PSA Certified.
 
 TF-M relies on an isolation boundary between the Non-secure Processing
 Environment (NSPE) and the Secure Processing Environment (SPE). It can but is
@@ -26,7 +25,7 @@
    :scale: 65 %
    :align: center
 
-   PSA FF compiant design with TF-M
+   FF-M compliant design with TF-M
 
 Applications and Libraries in the Non-secure Processing Environment can
 utilize these secure services with a standardized set of PSA Functional APIs.
@@ -76,9 +75,9 @@
 ************
 Prerequisite
 ************
-Trusted Firmware M provides a reference implementation of PSA specifications.
-It is assumed that the reader is familiar with PSA concepts and terms. PSA
-specifications can be found at
+Trusted Firmware M provides a reference implementation of platform security
+architecture  reference implementation aligning with PSA Certified guidelines.
+It is assumed that the reader is familiar with specifications can be found at
 `Platform Security Architecture Resources <https://developer.arm.com/architectures/security-architectures/platform-security-architecture>`__.
 
 The current TF-M implementation specifically targets TrustZone for ARMv8-M so a