[text-auditor] Batch fix clear runtime/CLI/docs text errors

## Text Improvements

The following user-facing text issues were found in the repository. Each is a low-effort fix.

### 1. Typo in Endpoint TLS error message

**File:** `internal/pkg/agent/application/endpoint_component_modifier.go` (line 176)
**Current text:** `EndpointTLSComponentModifier: could not covert modified config to expected config: %w`
**Suggested fix:** `EndpointTLSComponentModifier: could not convert modified config to expected config: %w`
**Why:** Clear misspelling (`covert` -> `convert`) in an operator-facing returned error.

### 2. Grammatically broken runtime connection error appears in two paths

**File:** `pkg/component/runtime/runtime_comm.go` (line 230)
**Current text:** `component cannot connect being destroyed`
**Suggested fix:** `component cannot connect while being destroyed`
**Why:** Missing connector word makes a user-visible gRPC error ungrammatical.

**File:** `pkg/component/runtime/runtime_comm.go` (line 345)
**Current text:** `application cannot connect being destroyed`
**Suggested fix:** `application cannot connect while being destroyed`
**Why:** Same grammar issue in the parallel application path.

### 3. `enroll` help text has duplicated and incorrect wording

**File:** `internal/pkg/agent/cmd/enroll.go` (line 72)
**Current text:** `Replace token that that allows the Agent to be replace with the provided --id as long as this token matches`
**Suggested fix:** `Replace token that allows the Agent to be replaced with the provided --id as long as this token matches`
**Why:** Contains both duplicated `that` and wrong verb form (`be replace`), making help text clearly incorrect.

### 4. Grammar error in artifact-signing documentation

**File:** `docs/pgp-sign-verify-artifact.md` (line 127)
**Current text:** `keyring to use, as the file do not exist, it'll create it`
**Suggested fix:** `keyring to use; if the file does not exist, it will be created`
**Why:** Clear subject-verb disagreement (`file do`) in user-facing docs.

### 5. Known-issues text is ungrammatical and hard to parse

**File:** `docs/release-notes/known-issues.md` (line 267)
**Current text:** `Users will see error failing with an error containing ... or other agent logs files:`
**Suggested fix:** `Users will see an error containing ... in ... or other agent log files:`
**Why:** Multiple clear grammar defects in one sentence (`see error`, `error failing`, `logs files`) reduce readability in a troubleshooting section.

## Suggested Actions

- [ ] Fix `covert` -> `convert` in `internal/pkg/agent/application/endpoint_component_modifier.go`.
- [ ] Replace both `cannot connect being destroyed` messages with `cannot connect while being destroyed` in `pkg/component/runtime/runtime_comm.go`.
- [ ] Fix duplicated/incorrect wording in the `replace-token` flag description in `internal/pkg/agent/cmd/enroll.go`.
- [ ] Correct grammar in the keyring bullet under `docs/pgp-sign-verify-artifact.md`.
- [ ] Rewrite the known-issues sentence for grammatical clarity in `docs/release-notes/known-issues.md`.

---
[What is this?](https://ela.st/github-ai-tools) | [From workflow: Text Auditor](https://github.com/elastic/elastic-agent/actions/runs/34355156281)

Give us feedback! React with 🚀 if perfect, 👍 if helpful, 👎 if not.
> - [x] expires on Sep 16, 2026, 1:18 PM UTC

Review the five named files: internal/pkg/agent/application/endpoint_component_modifier.go, pkg/component/runtime/runtime_comm.go, internal/pkg/agent/cmd/enroll.go, docs/pgp-sign-verify-artifact.md, and docs/release-notes/known-issues.md. Start by checking each referenced line and run the relevant Go and documentation checks available in the repository. Done means all listed user-facing messages and documentation sentences match the corrected wording without unrelated changes.

Written by the indexing model from the issue text.