Docs: Fix rst syntax errors

At documentation generation some warning was raised.

Change-Id: If277951d8d0f0b6c2a43d6cc835f733cdafaadd0
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
diff --git a/docs/user_guides/services/tfm_crypto_integration_guide.rst b/docs/user_guides/services/tfm_crypto_integration_guide.rst
index 7fcac0e..4ff06ea 100644
--- a/docs/user_guides/services/tfm_crypto_integration_guide.rst
+++ b/docs/user_guides/services/tfm_crypto_integration_guide.rst
@@ -54,9 +54,9 @@
   cipher/hash/MAC/generator operations, a context is associated to the handle
   provided during the setup phase, and is explicitly cleared only following a
   termination or an abort
- - ``tfm_crypto_secure_api.c`` : This module implements the PSA Crypto API
+- ``tfm_crypto_secure_api.c`` : This module implements the PSA Crypto API
   client interface exposed to the Secure Processing Environment
- - ``tfm_crypto_api.c`` :  This module is contained in ``interface\src`` and
+- ``tfm_crypto_api.c`` :  This module is contained in ``interface\src`` and
   implements the PSA Crypto API client interface exposed to the  Non-Secure
   Processing Environment.
 
diff --git a/docs/user_guides/tfm_secure_boot.rst b/docs/user_guides/tfm_secure_boot.rst
index 066d916..d37b775 100644
--- a/docs/user_guides/tfm_secure_boot.rst
+++ b/docs/user_guides/tfm_secure_boot.rst
@@ -84,7 +84,7 @@
 memory slot.
 
 Overwrite operation
-==================
+===================
 Active image is stored in slot 0, and this image is started always by the
 bootloader. Therefore images must be linked to slot 0. If the bootloader finds
 a valid image in slot 1, which is marked for upgrade, then the content of slot 0
@@ -201,8 +201,10 @@
 ********************
 MbedTLS library is used to sign the images. The list of supported signing
 algorithms:
-    - RSA-2048
-    - RSA-3072 (default)
+
+  - `RSA-2048`
+  - `RSA-3072`: default
+
 Example keys stored in ``root-rsa-2048.pem`` and ``root-rsa-3072.pem``.
 
 ************************
@@ -290,7 +292,7 @@
 firmware package, TF-M is built twice with different build configurations.
 
 Overwriting firmware upgrade
-=========================
+============================
 Run TF-M build twice with two different build configuration: default and
 regression. Save the artifacts between builds, because second run can overwrite
 original binaries. Download default build to slot 0 and regression build to